Why did pausing the game render it unplayable in multiplayer? What the actual fuck?
This isn't unheard of, however the devs have said it has something to do with the ping of players in a multiplayer game. So most likely one of your connections deteriorated during the pause, rather than the pause being the cause.
I won't claim to fully understand why it happens, however typically after a half an hour, the issue resolves itself. If you're only playing with human players its not too bad, you all have the same situation. If you're comp stomping I guess that can be quite annoying, as the AI isn't really affected, but it is only AI.