I am not 100% sure that this is a bug, but I’ve observed this behavior several times since the team mode was released, and surely it is not normal behavior.
At the end of a quickplay game, when 5 people want to rematch and the last slot is free, the game never starts. It just happened to me right now and we waited for about 5 minutes before people started leaving. We could see on the bottom right “2 in matchmaking”, “8 in matchmaking”, and so on with fluctuating numbers, but nobody was ever matched to our room.
Usually when this happens, quitting the room and selecting quickplay again will give you a match in just a few seconds.