For Reaper 5000

Is there currently a bug with the health pool of Foe Reaper 5000 in Deadmines? I'm in a group of level 17s and I've been attacking him for a good 5 minutes and his HP isn't budging.

He has 7604k HP and my top dps after 5 minutes has done 80k dps to him

I've had to hearth out, he wasn't doing enough dps to kill anyone, and we couldn't do enough dps to kill him either.