It is also worth mentioning that there are two Record-Route headers, the first one is the correct one and contains a valid value, and this extra one which does not appear in the egress INVITE in the pcap.
I've checked the msg_translator.c source file and there are many
of `LM_CRIT("FIXME: {message}\n");` calls, and I wonder if the
"FIXME" tag relates to the location of the error: a Kamailio
error or there is an issue in the user code.
Could I have more information about the "FIXME" tag?