Unable to drop the “Hammer of Kamasa” quest item in act 2

In the quest titled Treasure of Utzaal in the molten vault area with the lava boss I killed the boss several times after restarting the instance and have been unable to even drop the “Hammer of Kamasa” to complete the quest at all. TLDR hammer of Kamasa doesn’t drop from the boss in the molten vault area so I’m unable to complete the quest pls help