I’ve been experiencing this issue since 29.00 and there seems to be no pattern to it other than the items being recently placed or moved since the update and it effects not just props but devices as well. At first I thought it was only happening to duplicates but this actually effects assets dragged from the content drawer as well. I’d almost say that this may be the result of issues with revision control given it seems to imitate a rollback of sorts.
The deletions do not appear in the Undo Log and creative devices that referenced them still retain the reference but if you use them to see the object nothing happens because it no longer exists.
It is reaching the point where I’m needing to redo the same work multiple times to replace what the editor has decimated. But what I have noticed is that it ONLY starts to happen when a session is active. I’ve worked for hours without a sesssion opened and within an hour of the session active you begin to see objects getting deleted.