NavMeshBoundsVolume not created on imported FBX model

Is there anything special I need to do to an imported fbx mesh (just a simple cube at this stage) to make a NavMeshBoundsVolume calculate properly?

I have placed a basic UE cube of the same dimensions alongside an imported FBX cube and created a NavMeshBoundsVolume around them. The green RecastNavMesh-Default shows up green (when ‘p’ is pressed) just on the UE cube, and not the fbx cube.

yes I have the same problem