Hey, I don't know if it's a bug, but in my playthrough 2 characters went to the next level and the red one fell of the platform
It was a game that we made for a game jam in a week so, this bug must've slipped under our radar. I think it's not a thing that happens every time you play though so, resetting the game could fix this issue. We are really sorry that you wen't through this and We hope you still enjoyed the game.