In the real world, that really shouldn't be happening, but hey we are not working in the real world are we!?
As Rebekah said check your frame rates, also double referencing is a big no nooooooo (in slow mo)
Probably something to do with reference edits, my personal favourite, that would be my first port of call...
Failing that go back to the original scene with the ref and do cleanup (outliner - turn off DAG etc, look for unwanted nodes etc) then import
that ref as your master scene.
Then reference that...
Alternatively you could use geo cache or alembic
perhaps??
referencing in Maya is still very unstable and still in Ju Ju land especially when it comes to keyframing, and,,,,especially in the graph editor...
I noticed recently that hotkeys stop working in the graph editor after a while, but hey lets not get started on that topic...
Phin
Phinnaeus O'Connor Ltd
3D Animation for TV and Film