How Can I Have a Floating Mesh Block Navigation?

For an RTS game I’m making, I want one of the buildings to be kind of hovering above the ground, but I still want units to navigate around it like they would if it were a block of the same dimensions on the ground.

I tried having the capsule component affect the navigation, but nothing changed. I tried adding a new box collision with the same settings, but still nothing changed. How can I get the floating mesh/building to block ground navigation?