Tamed Ylth Spewer stops moving or attacking after leashing

I managed to tame a Ylth Spewer, and something about the AI is buggy. If it ever leashes (reappears next to you if you move too far away) the spewer stops moving or attacking. It doesn't even try to approach you if you move away from it a bit.

I don't see this behavior with other tamed beasts. Deactivating and reactivating will temporarily fix the issue. But its so slow compared to player speed it will inevitably leash and break again.