Hello Juha,
I think we have experienced the same behaviour (also `service kamailio restart` does strange things like freezed processes and failure of reloading procedure)
we solved starting with no rtpengine
this produces at startup:
WARNING: rtpengine [rtpengine_db.c:100]: rtpp_load_db(): No rtpproxy instances in database
and then, after rtpengine instances are up and correctly running we send an `rtpengine.reload` to kamailio
Note that after the startup, if an rtpengine instance fails no hangs in kamailio just put in disabled state and everything works!
Cheers
Paolo Visintin
CTO