I haven't seen anyone speak on this but this has happened to me twice today but I have no footage. I managed to find a youtube clip though As you can see Fury isn't targetable which clearly isn't intended even though one should focus fire on a pet. Regardless it's guaranteed free damage with no way of killing them.
Mother of Zod stop spamming the same combos Yes, I know that wasn't you. Still get's to me though. And I do remember hearing about this. Some people thought it had to do with people spawning them in PvE before the instance but all I've heard are rumors as to what causes this.