Seems simple enough right? I added a new AI package, picked playerfollow, and it follows me around

When I zone out of whiterun (or any loading gate'd city) into the overworld, they don't accompany me. If I fast travel with them next to me they will accompany me, they will follow me into houses/etc, but will not pass the gate to a city (from the inside out or outside in) unless I fast travel past the gate with them in tow

Anyone know?