Yep, you must have a cat with prowl. I had this issue as well. Just click the prowl button on the pet bar and it should stop. Prowl slows them down, but makes them invisible. There are pros/cons to this. You can always use prowl later to sneak up on someone.

Hes on prowl, Look on your pets action bar (Should be right above urs) and click on it, It should come off.

I am assuming your NE is a hunter? You probably trained a cat with prowl. Go into your pet tab in your spell book and right click “prowl” to turn it off. Your pet will move like normal