Yes, this happens to mine also.

I believe it has to do with the path-finding of AI. Is it happening while you're riding, or just when they're following you/patrolling? AI cant walk on floors, ramps, etc just the regular ol ground, its why you can stand on a rock/post and be safe from them.

Well today I was pulling my cart in our base building and my pet was half under the floor. I got on her and she immediately came up to floor level. I was then able to ride her up 2 levels using ramps. On dismounting she fell back down to the ground. I then set her to patrol and then another tribe member (my wife) reported the pet wandering around pulling my cart. I could see it on her screen but on mine the pet had no cart. Quite interesting as the pets aren't attached to the cart in any way even though the graphics show it that way.

Yup. Proper collision and path finding on player built surfaces is an ongoing task. Currently wild animals (non pets) should avoid all player built structures. It's more difficult with pets.

Anyways, I will leave this open. It's a known issue that will take a while to resolve.

Thanks for the reply and update. Happy to know it's being worked on sorry (for you) to hear that it's not an easy problem to solve.