Distro: pjsip Outbound Proxy settings from GUI don't appear in the config files

Title pretty much says it all; Using the distro image with all updates (FreePBX 13.0.189) and a largely vanilla config, creating a pjsip trunk and specifying the outbound proxy for that trunk seems to have no effect on the config files (in /etc/asterisk, ‘grep someRelevantSearchString *’ yields no result).

The outbound proxy certainly isn’t used; SIP traffic, such as OPTIONS or REGISTER requests are sent directly to the resolved IP address of the SIP server. Likewise, OPTIONS requests coming from the softswitch via the specified proxy fail to match the trunk: (res_pjsip_endpoint_identifier_ip.c:113 ip_identify_match_check: Source address proxy:port does not match identify ‘trunkname’).

I’ve tried formats such as “sip:softswitch.example.net” with and without ports, and just plain IP addresses to no avail. I even tried the ;lr flag just to see if there was any effect. None, either in the config files or the resulting SIP headers. It really looks like the GUI just ignores the field entirely.

An equivalent configuration using chan_sip works just fine. I’m not tied to either method, but it would be nice to know why I can’t make it work on pjsip… Any help?