I’m having the same issue on PPro CS6. Sometimes it plays, sometimes it doesn’t. It’s not choppy or anything it’s like the playback button stops working sometimes. I can scrub through footage just fine, rendered and unrendered.
Only solution I’ve been able to find is to close EVERY program on my computer, then just open Adobe, then I can start to open a couple other minor programs, but other CPU/RAM hungry programs tend to make PPro very unhappy.
That’s what I’ve been able to figure out so far. My blackmagic playback still doesn’t work right yet though.