I have Kamailio 4.4 proxying a "normal" call and am finding that it is crashing consistently when it tries to proxy the 200OK from a BYE request when dealing with a certain endpoint.

The SIP looks very normal to me and I've managed to obtain a trace, full debug logs and a core dump of the issue.

I can provide full copies of the files but the interesting parts from the logfile are here: https://pastebin.com/QkwVMxJj

bt output from the coredump is here: https://pastebin.com/auNRaeaU

Can anyone please advise?