We aren't doing the hashing of these files at all. RetroAchievements hasher application does it. If their app can't hash your file you'd have to wait for them to update the app. They just pushed out a new version and it'll be including in the next release, but in my CHD files where the v1.4 was failing v1.5 still fails as well (though it gives a reason now, and does so much faster)