Act VII: Vessel of hatred; All Good Things - Cannot be completed in HC

Hardcore
1

I finished the campaign in normal mode, but in HC the Harbinger jumps up on the ledge and becomes unattackable. I thought a bug and tried:

  1. T2, with Merc on a Spiritborn (first time it happened)
  2. On Normal, blasting through it
  3. T2 without Merc on Spiritborn
  4. Just standing there and letting thorns kill the adds
  5. Running away from the adds for a good 30 sec while dialogue happens then killing them

Is this just HC that you cannot finish the campaign? I did a search and I see all the posts about this but there are no responses from Blizzard dating all the back to Oct., so I am thinking it was either not meant to be completed on HC or I missed something that it won’t let me kill him. Any hints? Thxs!