I sometimes vs people and I get off his mystery landing it 1st turn & round, having the flying thunder tag onto them. From what I understand from his trigger he gets up to 10 extra attack for every opponents with that status. Sometimes he only does 1 attack even though they got the status and there is no debuffs on him. I saw this happened when I vs a cpu of me, both of us do the mystery and both hitting and having the same amount of the tags but I only do 1 attack while cpu version does multiple.

Also not sure if this is a bug ,but some characters heals the amount of damage they do even though they do zero damgage. Example Naruto 6 path after his mystery he heals based on his ninjutsu attack damage dealt and hits madara edo tensei who is immune to ninjutsu, but still gets healed.