Solution Found!!!
I had this problem. I tried so many things. The last thing I did was delete my profile under game data, doing this deleted my campaign, however, it allowed me to join into games. I told my friend (who was also having the same problem), and it didn't work the first time, but after doing a second it a second time, his game was working (relatively) fine. This may not be a permanent fix, but at least its something for now. I still have other random game freezes, but they don't seem to be related to this particular problem. Hope this helps.