geometry LOD is a bit particular.
If has to be simple and made up of closed convex shapes. (boxes, cylinders etc)
I think its selections have to be named
component01
component02
...
etc.
Run
Structure -> Conexitivy -> Find non convexivities and it will show you areas that are not correct.
The Geo LOD should be simple - T72 tank in demo had 1500 faces in primary LOD but the Geometry had only 40. Thats the number you are looking for in your house.