There is a bug with the "Red Hands" run boss-pair in Northern Elsewhere: the big and small Khajiits, Akumjhargo and Zav-i.
The bug has happened twice: When you kill ONE of the pair, the other despawns - literally disappeared in mid-fight although it had over 50% of its health left, because we focused one down before concentrating on the other - and thus cannot be killed until the area resets.
It's a new bug, I have not seen it before, it didn't happen when I last did the area on a different character.
And it happened BOTH when I killed the big one first, and when I killed the little one first.