The Nether Gauntless boss in the Nether doesn't work.

[NnAaTE]

Now, the boss spawns and everything, don't get me wrong. What it does do is literally anything else.

Doesn't take damage, doesn't move, and doesn't deal damage either. Just a lil brain dead puppie

[NnAaTE]

As it turns out, hitting it in the eye with any normal object that ISN'T a weapon with the new combat animation, it will re-initiate the fight.