So I've been having intermittent issues with mxf files in Premiere working on a very complex documentary with about 50 tb of media... The symptoms have been weird flashing on playback (and export) and occasional errors on playback and export (don't remember exactly what they were.). As always, the board has been a great resource and I was told modify: interpret the clips to change the color space to rec709 which seemed to work. And it also fixed the prores proxy files so I didn't have to recreate them... Friday, suddenly the problem reappeared on one clip (afaik- didn't check the thousands of media files). My client was upset (rightfully so) although we were still able to play and edit with the proxy files without issue. I checked and there was a premiere update available (we've been working on a mac) which I installed and it fixed the problem. This was the latest update (as of Friday) but didn't bother noting which version we had been working on.