I'd like to second the comment on the fact that fences is now trying to open certain documents directly in the portal fence, pdfs in particular. This does weird things to the fence and stops the back button working, so there needs to be a way to stop it, and just do folder traversal.
So far so good, I've recreated the portal without a crash and the new subfolder viewing is a big improvement.
I have been using Fences 4 and google drive without issue for a few days but as of this morning it crashes explorer when the folder portal to a Google Drive subfolder loads. I have a fences_debug_info.txt and crashdump, but they are too big to upload. If Stardock is interested I can provide them. Deleting the portal stops the crashing.