The Creepy Crate summoned by https://www.wowhead.com/spell=100684/creepy-crate

This companion/pet is not eating critters. When the pet eats a critter its supposed to show one of the three animations this pet has. The animations seem to work, I have seen the tongue lick animation and the green gas animation, havent seen the third animation yet (sure it works).

So basic problem: the pet doesnt eat critters

Recreate: just summon the pet, stand near a critter and see if it eats it.