Mob stops moving and can't be targeted by totem

Was using a frost wall totem and shield charge, with tempest shield active. Possibly also groundslamming.

I was attacking a bunch of bridgemen and a couple bigger monsters. Gorethrash was the last standing and eventually stopped chasing me.

He will still attack if I move into melee range but frost wall totem will not target him.

The damage I'm dealing also seemed lower than normal though I can't confirm that it was bugged.

It looks like he may be stuck on a rock dude corpse