so i’m doing the stealth tutorial, onto chapter 4 now, i’ve just baked my very first navmesh.
The tutorial specifically mentions to set the bake height of the navmesh to at least 1, and it specifically mentions the reason for this is to ensure that the navmesh doesn’t try to go under the Battle Bus in the centre of the map.
Well here it is: 
my navmesh going straight under the battlebus. I did exactly as suggested. Moreover, i’ve tried increasing the height to 2 and that didn’t solve anything
The battle bus itself does not have any colliders, and i suspected that as the issue, however a little quick testing indicates otherwise. As can be seen in the image, there’s an invisible wall which runs around it, which is part of env_stealth_static.
In fact, there are hundreds of walls just like it all over the scene, and the navmesh is not respecting any of them, as shown here: 
It stops at objects, but not at the invisible boundary walls which are the actual colliders, and which determine where actors can go. If i try to run AIs through this it’s just going to be a horrible mess, surely.
What’s going on here? how can i fix it?