Group error in solo matches

I've been experiencing this error frequently. When I join a solo match, the game sometimes assumes I'm in a group and says "Waiting for players to join." However, I'm playing solo and wasn't in a group before. I've already opened the game and played two or three missions solo, and the next time I get this waiting for players error.

The worst part is that I can't access the game menu and can't leave the match. This is another problem: the lack of a menu within the missions to exit, preventing me from playing and forcing me to restart the game frequently, not to mention the long server queues.