Here’s how i used nav mesh in my paper 2d project. Set the tilemap or floor sprites to collision thickness of 500. I’m using tilemaps for creating my levels. So my tilemap is set to 0 on the Y coordinate. Placed a nav mesh volume at y=-50, resized to x-length of the floor, y=100, z=10 (height). Placed the nav mesh volume where the floor is. If you press P in the editor, it should calc the navigation, and show a line in green. There is a few issues with using tilemaps though, which i’m trying to fix. If you have 2 walking floors, 1 above another, the shorter length floor’s nav is used for both floors, even if I placed each floor it’s own nav mesh volume. Also, if nav mesh calc is set to Dynamic, the AI is not moving until I interact with it, so best to use Dynamic with Modifiers.
Hope this helps you.