I've lost the ability to Edit in Place?

Sometime over the last few weeks I've lost the ability to Edit in Place in Animate CC; when double-clicking and even when right-clicking and choosing "edit in place", the editing instead happens in isolation from everything else, so I loose all reference of other graphics that I'm trying  to line things up with.  ie. it's like editing a symbol directly from the library.
Any thoughts on what's happened?  As far as I'm aware there have been no settings changes.