Grid graph on rooms with ceilings

Hello all,
We are constructing a game where in one of the scenes a maze is generated with ceilings and there will be monsters chasing around. The maze is generated at run time so when the grid graph is applied i will be applied on the ceiling instead of the floor so the monster is always trying to go up and then stuck.
Could you please provide me some hint if there is anything I should look into so the grid graph will be applied on the floor only? One workaround I have found out is to set the ceiling layer to “ignore raycast” from “default” and perform a scan()… but it should be a side effect.

Thanks in advance.

Hi

You will have to put the ceiling in a separate layer (though not necessarily “Ignore Raycast”), how else should the system know what is ground and what is ceiling?