Might as well report this now that I made an account here. I can’t remember the details but:
In the survival mode a double K.O. doesn’t end the match but instead the game goes to a state where the next opponent is just jumping around the screen indefinitely and you have to exit through the pause menu. This didn’t seem to happen with shadow bosses (or maybe it was the opponent before a boss?). Other than that, this seemed to happen every time.
I’m almost certain this still happens in the latest version (PS4. / 1.21) but as I said, I’m not really remembering the details.