Acid spit collects corpses. Maybe bug? Also make sure you bring the saddle into the cave with you, or you will spend many aggravating hours trying to get it to follow you out, as it gets stuck on every little thing.
This Dino has a turret mode and on mobile it doesn’t move unless that turret mode is off. It is also a good choice for base defense for this ability and being able to deal torpor and blind people it’s is one of the best defensive dinosaurs.