Legend of the koro king

When you start a game in any other maps you can choose your champion and you can just leave without locking your pick. But why the hell you can not do that in the Legend of poro king? I choose my champion without locking and went to do something else but when I returned I see that the game has not started. Thinking that someone dodged I try to start a new game but a message pops up saying that I dodged the game. I mean what the hell riot?