The issue with images that I experienced has been fixed by jonnyb in r44666 (trunk) and r44667 (10.x)
In the end the problem seems to be with image resize in one file gallery, not with local perms (the image was deleted after the resize, it seems).
Was your problem related to images getting resized in the file gallery? can you test his fix?
I hope you can test with some updated daily build of 10.x from tomorrow or so. See:
Or manually applying that fix. See changes here: