Last time I tried to start a mission, it failed to connect.
Now I always get the message "Mission active. Try to rejoin?"
I can only choose "accept" or "cancel".
If I choose "cancel", I am in singleplayer, if I then go to Matchmaking, the question pops up again.
If I choose "accept", it tries to rejoin, fails and asks me again.
Basically, I cannot play online anymore, since the game always wants to rejoin that one mission, and fails doing that. It doesn't seem to want to search for a new game.