After taking the portal from Dealer Xy’exa, the Mythresh got aggro on someone, but not instantly, it only snapped to us when we were half way done with the last boss (Mueh’zala). Made us wipe a +15 when we still had 5 minutes left before pull.
This just happened to us, it cost us +15 time, since it caused a full wipe a minute after we started the fight.
Im waiting for the day when Blizz give you credit for failed keys due to their own bugs.
Just had a +15 key killed because of this too. Fuming because we had a perfect run until a known bug bricks the key. Unreal from Blizzard this hasn’t been addressed. Imagine if this happened during MDI