I don't believe it's fixed in the actual release, but I haven't confirmed. I'd expect there would've been an announcement if it were. You could probably download the latest XF and compare the appropriate file with the patch that
@Jeremy P posted here:
I've attached a patch, you'll need to unzip it and replace the enclosed js/xf/attachment_manager-compiled.js
file, which should resolve this. You'll want to rebuild the master data and/or clear your browser cache to pick up the changes, too.