Severity: I would say 1 because this game automatically disconnects you from the game automatically.
This happens when you create a game and as you want to change or to press back to leave this lobby, you will get disconnected 100% of the time. I've tried it arround 7 times before reporting this bug and it happens constantly without fail.
To anyone reading this that is not a developer, try to pick the mission you want to play carefully and be sure you do want to play that specific map, because if you make a mistake you will get dc by pressing back.
Thank you devs for your time! :)