Act 3 Hammer of Kamasa not dropping from Boss

Im on the Treasures of Utzaal quest in Act 3 on my second character and the Hammer of Kamasa isn't dropping from the boss. I've already restarted the instance of the dungeon and retried the fight 4 times and it refuses to drop.

On the first instance I was playing with a friend and it dropped for him so I retried it and it never dropped or showed on the map as a drop even after removing item filters, restarting the game, etc.