Mephisto being damaged while regen against new Thor

As title says, Thor used his 3rd special and I was being shocked... however when my Mephisto went into regen mode... it just KOd me instantly... I'm sure he isnt supposed to take any damage while regenerating?
3
Comments
Nope
Fought a Mephisto in valor quest just now with GP. The regen stopped the bleed damage.
Unrelated: why does "IMMUNE" text pop up while fighting Mephisto with GP?
I just tried it in a duel with GP, AA, and Blade. Yes with Blade (danger sense), no with GP and AA. I used her and AA to bleed him to death before despite regen before I pulled Blade. Must have been a bug that got fixed quietly.
I think the IMMUNE message is in relation to GP ability accuracy effect when starting off the 1st combo of the match.