[BUG] b2b_entities:_b2b_send_reply: Tm transaction not saved!

[BTa7BxrHYn]

OpenSIPS version you are running

version: opensips 3.4.14 (x86_64/linux)
flags: STATS: On, DISABLE_NAGLE, USE_MCAST, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, HP_MALLOC, DBG_MALLOC, FAST_LOCK-ADAPTIVE_WAIT
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535
poll method support: poll, epoll, sigio_rt, select.
git revision: c0f532b
main.c compiled on with gcc 10

Describe the bug

A simple scenario for b2b_entities
For an incoming invite, I run ua_session_server_init($avp(b2b_key), "arhb");
After that, I need to send a 180 to the caller, then a 503 to simulate an error.

route{
            if (is_method("INVITE") && !has_totag() ) {
                 ua_session_server_init($avp(b2b_key), "arhb");
                 exit;
            }
}



event_route[E_UA_SESSION] {
     xlog("L_INFO", "E_UA_SESSION [$param(key)] $param(entity_type) key=$param(event_type)\n");

     if ($param(event_type) && $param(event_type) == "NEW"){
         if (!cache_fetch("redis:group1",$param(key), $avp(sess))) {
            ua_session_reply($param(key), "INVITE", 180, "Ringing");
            ua_session_reply($param(key), "INVITE", 503, "Service Unavailable");
         }
     }

}

I get an error

ERROR:b2b_entities:_b2b_send_reply: Tm transaction not saved!
ERROR:b2b_entities:b2b_prescript_f: Failed to send 200 OK reply

opensips.log

opensips-cli -x mi ua_session_list
shows the presence of a session

To Reproduce

Expected behavior

Relevant System Logs

OS/environment information

• Operating System:
• OpenSIPS installation:
• other relevant information:

Additional context