Brisket of the Bovine Chest drop rate??

I’ve already finished everything I wanted to do this season—cleared the challenges and min-maxed my character. My only remaining motivation is to finish farming the Bovine skin. I’ve run over 60 T12 Moophistos and had 3 Mythic Tributes drop, but that damn chest just won't drop.

I can't stand farming Prime Rib in the Cow Level anymore, ugh.

Am I doing something wrong? Is there a requirement I’m overlooking? Is anyone else having similar terrible luck?

By the way, in my opinion, this was the best season yet.