That doesn’t help. I know how to select and confirm a character. Same for my co-player. But then how do you start? Press start. What is start on that screen. Neither space nor enter works and the keys for the resp. player just affect the character panel for that player. They do not start the game.
I can confirm that the Enter key does nothing. This is on both Linux and Windows and on the same machine (a new latop I bought last summer). I will try on my macBook tomorrow. There is no other issue with the Enter key anywhere on Linux and/or Windows in any app so this is as WTF as it gets, I guess. :)