When I join a multiplayer lobby, the game can't start until I leave. Also, I can hit the ready/not ready button after the host has set the game to start. We aren't using mods.
We use Steam. I used to experience some degree of difficulty whilst in the lobby (couldn't see anyone and what not), but I fixed that and was then unable to play due to slowing down the game too much when we played with mods.I have no idea what could cause that, I'm sorry! A weird one.
Has this game always been like that, or it was okay up to some point?
If you are all on Steam you'll be using Steam MP. In our launcher's Game Settings menu select Cross Store MP (all players will need to do this) - do you get the same problem then?