Stacking TileMaps for Navigation2D, Zombie walks through walls

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:bust_in_silhouette: Asked By terrarum

I’ve made a TileMap scene that is a simple house, and I instanced that on top of a Ground tilemap which is an endless field of walkable grass tiles.

The scenes are arranged as so:

Navigation2D
    - TileMap(ground)
    - TileMap(House1)
    - TileMap(House2)

I created a path using get_simple_path to move a Zombie character from inside a house to a point outside and it walked straight through a wall.

enter image description here

It took me a while but I’ve realised that while my player-controlled Kinematic2D character gets blocked by the walls as expected, the Navigation2D path totally ignores the instanced houses and only cares about the ground TileMap, presumably because it’s the first one under the Navigation2D node? If I draw walls on the ground TileMap the path goes around them as expected.

Is there a way to have the Navigation2D behave the way I expect, or should I just draw everything in the one TileMap?

Thanks for any help you can give!