Layered Grid Graph scanning building interior

This Layered Grid Graph is mapping under the building and on the roof. How do I get it to recognize the floor of the building as a walkable surface?

Make sure you have a collider on the floor.

That’s the crazy part. I checked, and the whole thing has a collider that matches the mesh. Here’s the same scene with a Unity NavMesh. Scratching my head here. Any ideas?

Hey is that entire model using 1 mesh collider? if so, I had same issue and fixed it here: