diff --git a/.env.dist.testing b/.env.dist.testing
index 19caaa5..0ceb7d2 100644
--- a/.env.dist.testing
+++ b/.env.dist.testing
@@ -7,7 +7,7 @@ TEST_SITE_TABLE_PREFIX=wp_
 TEST_SITE_ADMIN_USERNAME=admin
 TEST_SITE_ADMIN_PASSWORD=password
 TEST_SITE_WP_ADMIN_PATH=/wp-admin
-WP_ROOT_FOLDER="/home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/wordpress"
+WP_ROOT_FOLDER="/var/www/html"
 WP_ENVIRONMENT_TYPE=local
 TEST_DB_NAME=test
 TEST_DB_HOST=localhost
@@ -17,7 +17,7 @@ TEST_TABLE_PREFIX=wp_
 TEST_SITE_WP_URL=http://127.0.0.1
 TEST_SITE_WP_DOMAIN=127.0.0.1
 TEST_SITE_ADMIN_EMAIL=wordpress@convertkit.local
-TEST_SITE_CONFIG_FILE="/home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/wordpress/wp-content/plugins/convertkit-wordpress-libraries/tests/_support/WpunitTesterConfig.php"
+TEST_SITE_CONFIG_FILE="/var/www/html/wp-content/plugins/convertkit-wordpress-libraries/tests/_support/WpunitTesterConfig.php"
 CONVERTKIT_API_BROADCAST_ID="8697158"
 CONVERTKIT_API_CUSTOM_FIELD_ID="258240"
 CONVERTKIT_API_FORM_ID="2765139"
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index ded4e07..fa5fba9 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -17,15 +17,15 @@ jobs:
 
     # Virtual Environment to use.
     # @see: https://github.com/actions/virtual-environments
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
 
     # Environment Variables.
     # Accessible by using ${{ env.NAME }}
     # Use ${{ secrets.NAME }} to include any GitHub Secrets in ${{ env.NAME }}
     # The base folder will always be /home/runner/work/github-repo-name/github-repo-name
     env:
-      ROOT_DIR: /home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/wordpress
-      PLUGIN_DIR: /home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/wordpress/wp-content/plugins/convertkit-wordpress-libraries
+      ROOT_DIR: /var/www/html
+      PLUGIN_DIR: /var/www/html/wp-content/plugins/convertkit-wordpress-libraries
       DB_NAME: test
       DB_USER: root
       DB_PASS: root
@@ -51,6 +51,13 @@ jobs:
 
     # Steps to install, configure and run tests
     steps:
+        # Checkout Plugin to /home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/convertkit-wordpress-libraries
+      # We cannot checkout to ${{ env.PLUGIN_DIR }} as GitHub Actions require it be first placed in /home/runner/work/repo/repo
+      - name: Checkout Plugin
+        uses: actions/checkout@v4
+        with:
+          path: /home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/convertkit-wordpress-libraries
+
       - name: Start MySQL
         run: sudo systemctl start mysql.service
 
@@ -65,17 +72,15 @@ jobs:
 
       # Some workflows checkout WordPress from GitHub, but that seems to bring a bunch of uncompiled files with it.
       # Instead download from wordpress.org stable.
-      - name: Download WordPress
-        run: wget https://wordpress.org/wordpress-${{ matrix.wp-versions }}.tar.gz
-
-      - name: Extract WordPress
-        run: tar xfz wordpress-${{ matrix.wp-versions }}.tar.gz
-
-      # Checkout (copy) this repository's Plugin to this VM.
-      - name: Checkout Plugin
-        uses: actions/checkout@v4
-        with:
-          path: ${{ env.PLUGIN_DIR }}
+      - name: Download and Extract WordPress
+        run: |
+          sudo chown -R runner:docker /var/www/html
+          ls -la /var/www/html
+          cd /var/www/html
+          wget https://wordpress.org/wordpress-${{ matrix.wp-versions }}.tar.gz
+          tar xfz wordpress-${{ matrix.wp-versions }}.tar.gz
+          mv wordpress/* .
+          rm -rf wordpress wordpress-${{ matrix.wp-versions }}.tar.gz
 
       # We install WP-CLI, as it provides useful commands to setup and install WordPress through the command line.
       - name: Install WP-CLI
@@ -97,6 +102,10 @@ jobs:
         working-directory: ${{ env.ROOT_DIR }}
         run: wp-cli plugin install ${{ env.INSTALL_PLUGINS }}
 
+      # Move Plugin
+      - name: Move Plugin
+        run: mv /home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/convertkit-wordpress-libraries ${{ env.PLUGIN_DIR }}
+
       # Install PHP version to run tests against.
       - name: Install PHP
         uses: shivammathur/setup-php@v2
diff --git a/phpcs.xml b/phpcs.xml
index 1e875f4..11ae28a 100644
--- a/phpcs.xml
+++ b/phpcs.xml
@@ -14,8 +14,8 @@
 	<!-- Exclude traits from the PHP SDK. -->
 	<exclude-pattern>class-convertkit-api-traits.php</exclude-pattern>
 
-	<!-- Check that code meets WordPress-Extra standards. -->
-	<rule ref="WordPress-Extra">
+	<!-- Check that code meets WordPress standards - this includes core, docs and extra. -->
+	<rule ref="WordPress">
 		<!--
 		We may want a middle ground though. The best way to do this is add the
 		entire ruleset, then rule by rule, remove ones that don't suit a project.
@@ -33,13 +33,11 @@
 		<exclude name="WordPress.Security.EscapeOutput"/>
 		-->
 		<exclude name="WordPress.PHP.YodaConditions" />
+		<exclude name="WordPress.DB.SlowDBQuery.slow_db_query_meta_query" />
 		<exclude name="PSR2.Methods.FunctionClosingBrace.SpacingBeforeClose" />
 		<exclude name="PSR2.Classes.ClassDeclaration.CloseBraceAfterBody" />
 	</rule>
 
-	<!-- Check that code is documented to WordPress Standards. -->
-	<rule ref="WordPress-Docs"/>
-
 	<!-- Add in some extra rules from other standards. -->
 	<rule ref="Generic.CodeAnalysis.UnusedFunctionParameter"/>
 	<rule ref="Generic.Commenting.Todo"/>
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 7dc6e9e..2cf5ef8 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -16,11 +16,11 @@ parameters:
 
     # Location of WordPress Plugins for PHPStan to scan, building symbols.
     scanDirectories:
-        - /home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/wordpress/wp-content/plugins
+        - /var/www/html/wp-content/plugins
 
     # Location of constants for PHPStan to scan, building symbols.
     scanFiles:
-        - /home/runner/work/convertkit-wordpress-libraries/convertkit-wordpress-libraries/wordpress/wp-config.php
+        - /var/www/html/wp-config.php
 
     # Don't report unmatched ignored errors on older PHP versions (7.2, 7.3)
     reportUnmatchedIgnoredErrors: false
diff --git a/src/class-convertkit-api-v4.php b/src/class-convertkit-api-v4.php
index cfde53e..3b72f5b 100644
--- a/src/class-convertkit-api-v4.php
+++ b/src/class-convertkit-api-v4.php
@@ -492,6 +492,7 @@ public function get_access_token_by_api_key_and_secret( $api_key, $api_secret )
 			array(
 				'api_key'    => $api_key,
 				'api_secret' => $api_secret,
+				'client_id'  => $this->client_id,
 			)
 		);
 
diff --git a/tests/wpunit/APITest.php b/tests/wpunit/APITest.php
index 27f2d03..b7531a9 100644
--- a/tests/wpunit/APITest.php
+++ b/tests/wpunit/APITest.php
@@ -604,6 +604,38 @@ public function testGetAccessTokenByInvalidAPIKeyAndSecret()
 		$this->assertEquals('Authorization Failed: API Secret not valid', $result->get_error_message());
 	}
 
+	/**
+	 * Test that fetching an Access Token using an invalid client ID returns a WP_Error.
+	 *
+	 * @since   2.0.7
+	 */
+	public function testGetAccessTokenByAPIKeyAndSecretWithInvalidClientID()
+	{
+		$api    = new ConvertKit_API_V4( 'invalidClientID', $_ENV['CONVERTKIT_OAUTH_REDIRECT_URI'] );
+		$result = $api->get_access_token_by_api_key_and_secret(
+			$_ENV['CONVERTKIT_API_KEY'],
+			$_ENV['CONVERTKIT_API_SECRET']
+		);
+		$this->assertInstanceOf(WP_Error::class, $result);
+		$this->assertEquals($result->get_error_code(), $this->errorCode);
+	}
+
+	/**
+	 * Test that fetching an Access Token using a blank client ID returns a WP_Error.
+	 *
+	 * @since   2.0.7
+	 */
+	public function testGetAccessTokenByAPIKeyAndSecretWithBlankClientID()
+	{
+		$api    = new ConvertKit_API_V4( '', $_ENV['CONVERTKIT_OAUTH_REDIRECT_URI'] );
+		$result = $api->get_access_token_by_api_key_and_secret(
+			$_ENV['CONVERTKIT_API_KEY'],
+			$_ENV['CONVERTKIT_API_SECRET']
+		);
+		$this->assertInstanceOf(WP_Error::class, $result);
+		$this->assertEquals($result->get_error_code(), $this->errorCode);
+	}
+
 	/**
 	 * Test that supplying valid API credentials to the API class returns the expected account information.
 	 *
@@ -756,8 +788,9 @@ public function testGetGrowthStatsWithStartDate()
 		$this->assertArrayHasKey('ending', $result['stats']);
 
 		// Assert start and end dates were honored.
-		$this->assertEquals($result['stats']['starting'], $starting->format('Y-m-d') . 'T00:00:00-05:00');
-		$this->assertEquals($result['stats']['ending'], $ending->format('Y-m-d') . 'T23:59:59-05:00');
+		$timezone = ( new DateTime() )->setTimezone(new DateTimeZone('America/New_York'))->format('P'); // Gets timezone offset for New York (-04:00 during DST, -05:00 otherwise).
+		$this->assertEquals($result['stats']['starting'], $starting->format('Y-m-d') . 'T00:00:00' . $timezone);
+		$this->assertEquals($result['stats']['ending'], $ending->format('Y-m-d') . 'T23:59:59' . $timezone);
 	}
 
 	/**
@@ -790,8 +823,9 @@ public function testGetGrowthStatsWithEndDate()
 		$this->assertArrayHasKey('ending', $result['stats']);
 
 		// Assert start and end dates were honored.
-		$this->assertEquals($result['stats']['starting'], $starting->format('Y-m-d') . 'T00:00:00-05:00');
-		$this->assertEquals($result['stats']['ending'], $ending->format('Y-m-d') . 'T23:59:59-05:00');
+		$timezone = ( new DateTime() )->setTimezone(new DateTimeZone('America/New_York'))->format('P'); // Gets timezone offset for New York (-04:00 during DST, -05:00 otherwise).
+		$this->assertEquals($result['stats']['starting'], $starting->format('Y-m-d') . 'T00:00:00' . $timezone);
+		$this->assertEquals($result['stats']['ending'], $ending->format('Y-m-d') . 'T23:59:59' . $timezone);
 	}
 
 	/**
@@ -1249,7 +1283,7 @@ public function testGetFormSubscriptionsWithBouncedSubscriberState()
 	 */
 	public function testGetFormSubscriptionsWithAddedAfterParam()
 	{
-		$date   = new \DateTime('2024-01-01');
+		$date   = new \DateTime('2022-01-01');
 		$result = $this->api->get_form_subscriptions(
 			(int) $_ENV['CONVERTKIT_API_FORM_ID'], // Form ID.
 			'active', // Subscriber state.
@@ -1312,7 +1346,7 @@ public function testGetFormSubscriptionsWithAddedBeforeParam()
 	 */
 	public function testGetFormSubscriptionsWithCreatedAfterParam()
 	{
-		$date   = new \DateTime('2024-01-01');
+		$date   = new \DateTime('2022-01-01');
 		$result = $this->api->get_form_subscriptions(
 			(int) $_ENV['CONVERTKIT_API_FORM_ID'], // Form ID.
 			'active', // Subscriber state.
@@ -2272,7 +2306,7 @@ public function testGetSequenceSubscriptionsWithBouncedSubscriberState()
 	 */
 	public function testGetSequenceSubscriptionsWithAddedAfterParam()
 	{
-		$date   = new \DateTime('2024-01-01');
+		$date   = new \DateTime('2022-01-01');
 		$result = $this->api->get_sequence_subscriptions(
 			$_ENV['CONVERTKIT_API_SEQUENCE_ID'], // Sequence ID.
 			'active', // Subscriber state.
@@ -2335,7 +2369,7 @@ public function testGetSequenceSubscriptionsWithAddedBeforeParam()
 	 */
 	public function testGetSequenceSubscriptionsWithCreatedAfterParam()
 	{
-		$date   = new \DateTime('2024-01-01');
+		$date   = new \DateTime('2022-01-01');
 		$result = $this->api->get_sequence_subscriptions(
 			$_ENV['CONVERTKIT_API_SEQUENCE_ID'], // Sequence ID.
 			'active', // Subscriber state.
@@ -2441,7 +2475,7 @@ public function testGetSequenceSubscriptionsPagination()
 
 		// Assert has_previous_page and has_next_page are correct.
 		$this->assertTrue($result['pagination']['has_previous_page']);
-		$this->assertTrue($result['pagination']['has_next_page']);
+		$this->assertFalse($result['pagination']['has_next_page']);
 
 		// Use pagination to fetch previous page.
 		$result = $this->api->get_sequence_subscriptions(
@@ -2654,7 +2688,7 @@ public function testCreateTagBlank()
 	}
 
 	/**
-	 * Test that create_tag() returns a WP_Error when creating
+	 * Test that create_tag() returns the expected data when creating
 	 * a tag that already exists.
 	 *
 	 * @since   1.0.0
@@ -2664,8 +2698,12 @@ public function testCreateTagBlank()
 	public function testCreateTagThatExists()
 	{
 		$result = $this->api->create_tag($_ENV['CONVERTKIT_API_TAG_NAME']);
-		$this->assertInstanceOf(WP_Error::class, $result);
-		$this->assertEquals($result->get_error_code(), $this->errorCode);
+
+		// Assert response contains correct data.
+		$this->assertArrayHasKey('id', $result['tag']);
+		$this->assertArrayHasKey('name', $result['tag']);
+		$this->assertArrayHasKey('created_at', $result['tag']);
+		$this->assertEquals($result['tag']['name'], $_ENV['CONVERTKIT_API_TAG_NAME']);
 	}
 
 	/**
@@ -2734,8 +2772,8 @@ public function testCreateTagsBlank()
 	}
 
 	/**
-	 * Test that create_tags() returns a WP_Error when creating
-	 * tags that already exists.
+	 * Test that create_tags() returns the expected data when creating
+	 * tags that already exist.
 	 *
 	 * @since   2.0.0
 	 *
@@ -2750,8 +2788,10 @@ public function testCreateTagsThatExist()
 			]
 		);
 
-		// Assert failures.
-		$this->assertCount(2, $result['failures']);
+		// Assert existing tags are returned.
+		$this->assertCount(2, $result['tags']);
+		$this->assertEquals($result['tags'][1]['name'], $_ENV['CONVERTKIT_API_TAG_NAME']);
+		$this->assertEquals($result['tags'][0]['name'], $_ENV['CONVERTKIT_API_TAG_NAME_2']);
 	}
 
 	/**
@@ -3127,7 +3167,7 @@ public function testGetTagSubscriptionsWithBouncedSubscriberState()
 	 */
 	public function testGetTagSubscriptionsWithTaggedAfterParam()
 	{
-		$date   = new \DateTime('2024-01-01');
+		$date   = new \DateTime('2022-01-01');
 		$result = $this->api->get_tag_subscriptions(
 			(int) $_ENV['CONVERTKIT_API_TAG_ID'], // Tag ID.
 			'active', // Subscriber state.
@@ -3190,7 +3230,7 @@ public function testGetTagSubscriptionsWithTaggedBeforeParam()
 	 */
 	public function testGetTagSubscriptionsWithCreatedAfterParam()
 	{
-		$date   = new \DateTime('2024-01-01');
+		$date   = new \DateTime('2022-01-01');
 		$result = $this->api->get_tag_subscriptions(
 			(int) $_ENV['CONVERTKIT_API_TAG_ID'], // Tag ID.
 			'active', // Subscriber state.
@@ -3450,7 +3490,7 @@ public function testGetSubscribersWithBouncedSubscriberState()
 	 */
 	public function testGetSubscribersWithCreatedAfterParam()
 	{
-		$date   = new \DateTime('2024-01-01');
+		$date   = new \DateTime('2022-01-01');
 		$result = $this->api->get_subscribers(
 			'active', // Subscriber state.
 			'', // Email address.
@@ -3507,7 +3547,7 @@ public function testGetSubscribersWithCreatedBeforeParam()
 	 */
 	public function testGetSubscribersWithUpdatedAfterParam()
 	{
-		$date   = new \DateTime('2024-01-01');
+		$date   = new \DateTime('2022-01-01');
 		$result = $this->api->get_subscribers(
 			'active', // Subscriber state.
 			'', // Email address.