If I insert a new model in a running world that (seems to have) reached a stable position, I get what looks like a strange influence on the pre-existing model - as if there was a joint between them.

recording: https://imgur.com/a/URSO81O

I'm using the "nested" model uploaded as part of https://github.com/osrf/gazebo/issues/2807 and wondering if there would be a link with the strange behaviour I reported at https://github.com/osrf/gazebo/issues/2806