Twinned Core Malachai & Piety Invincible

https://imgur.com/a/3Ee0k

Decided to roll a twinned core map for challenge. In the first stage both Malachais became invincible as well as Piety so there was literally nothing I could do to beat the fight. I tried doing damage for about a minute before letting myself die. Is this intended? Am I supposed to get both Malachais to the same hp at the same time or something?

I also got the same bug, got one malachai down to 50% then the other wouldnt budge from around 70%. Had to leave the map after 4 minutes of trying.