Okay it should be working now. I put in extra checks. I got it to work a good 5 or 6 consecutive times for myself, anyway.
It updated on my first try this time! I'll be running an alt through soon. I'll reply here if I have trouble again.
I was just having problems with this, am playing as a Necromancer on Varsoon. I tried deleting quest and retaking it (the boar stayed but was refreshed by fortune teller) and finally tried despawning my Undead Knight pet and attacking a shroom on the edges of the indented area. Quest finally updated when I ran back into the indention area after killing a shroom without the pet.