Thanks Dustinmaertz for letting us know! For the record I bumped into the issue once with 1.6 (masks becoming half-res) but as of 1.7 this should now be permanently fixed. - Teddy
Wow 1048 samples is insane, I usually use 128-256 samples. Have you checked to make sure there are no overlapping uv's or double faces in your geometry?
Hmm, this was an issue we faced in earlier versions and this is the first time I´ve seen it lately, does it help if you do a clean install and upgrade to version 1.6?