Regarding `local_rport=yes`, it is somehow strange, because the code has the condition:
``` if((ksr_local_rport) || (msg && (msg->msg_flags&FL_ADD_LOCAL_RPORT))) { ```
`ksr_local_rport` corresponds to `local_rport` parameter and `FL_ADD_LOCAL_RPORT` is set by `add_local_rport()`. The cfg value `yes` it is an alias to integer `1`.
Can you double check using `local_rport=yes` and no `event_route[tm:local-request]`? It would be good to sort it out now, when we are on it.