trying to load .swf games from my HD and they won't play - just a blank screen. flash content from 4chan still works. there's been a bunch of updates to firefox in the past few days, and it's possible one of them broke this. i tried googling for an answer and got no useful results; firefox 55.0.2 (64-bit) under windows 10, if that means anything.

pic related, it's what i'd be doing if this still worked.