Create game bug

When I create a custom game and create a use map,
I get kicked out as soon as I enter and the game doesn’t get created.
And in the chat window, it says I’ve left, but I haven’t really left.
It says Player 0/1, and when I press the start game button, it doesn’t start.
For reference, I created a use map that can accommodate 8 people, but it says Player 0/1.