Question NavMesh not created on static and walkable objects, is this a bug?

Hi all, simple quick and easy. trying to place walkable objects on my navmesh. They're marked as static and as walkable, but the nav mesh doesn't bake them in. screenshot added. Any help?



https://imgur.com/gallery/50W48kX

Thanks!

 

I have realized it was happening because of the existence of water beneath the object, but that still doesn't help, seeing as the object I'm creating is a bridge.