Device: Bluestack emulator, Samsung Galaxy S7; 

OS: Android 7 and Android 8 Respectivelly

WTR (way to reproduce an issue):

Step 1: Go to Battle -> Campaing -> Any stage -> Any Level -> Multibattle.

Step 2:  make sure there is at least a combination of a max level champ that isn't the leader and any champ on the leader slot.

Step 3:  Make sure "Continue Multibattle Even when All Champions are Max Level" is activated. 

Step 4: Run Muiltibattle.

Step 5: ????

Step 6: no profit.

Description:

Mutibatlle is bugged: Max level champions doesn't stay even if it is explicity stated to stay even after barelly starting the battle.
An Image says more than 1000 words, a video says more than a 1000 pictures:
https://youtu.be/P-9IUcIvpAk
This issue was already reported by various other users, but I am just formalizing the issue.