We have encountered this too, the “fix” is to first make sure that the sequence settings Video Processing tab says “Always render in RGB”, and that the codec is set to the blackmagic rather than apple 8/10bit, second delete any video renders, and finally export the frame to quicktime without using quicktime conversion. We then use after effects or quicktime pro to get the frame to photoshop.
Sounds like a real pain but you get used to it. Frankly I’m delighted someone else has finally noticed it, it is a huge bug but I think most people who don’t need to hit a specific frame miss it. It has bitten us a lot of times (we make DVD’s too) but now all of our Final Cut users are trained in to this procedure. The Quicktime conversion output has always been buggy for us.
Glenn Stewart
1k Studios