I've created a cell, it's got a checked and finalized navmesh. It's got a door with teleport (that works) and the navmesh has the solid green triangle at the door beneath the teleport marker. The external cell also has the solid green navmesh tri beneath the teleport marker.

Follower will not cross in any direction.

The external cell, tho, might be problematic. the navmesh poly is beneath the surface of the ground, beneath the surface that the tport marker is on and is therefore significantly beneath the tport marker. Does that matter?

How would I fix this?

Is there a tutorial somewhere for making this transition work for followers/npcs?