Can't register for multiplayer on Linux/Steam

[catalina.out]

I've tried usernames between 4 and 10 characters and in each case I get the message "Your username must be less than characters long." No, you didn't just skip a word and neither did I, but the game did! Screenshot attached.

Let me know what to do to help troubleshoot, also interested in possible alternate ways to register.

Very cool single player modes btw.