I'm gonna play the next map when it comes to Xbox, and then move on to BO4; if there are similar issues I think I'll be done with the franchise. Which sucks 'cause it's been my goto fp shooter for a long time.
A fix still coming, so I hope it will be out by the time you are jumping back in for DLC 4 on XB1. I'll jump back on this thread if we get an ETA.
I've played through the Final Reich with one other person or solo, the map still crashes with three or four players. So at least you can get the first hidden challenge for the Cold Blooded character.