I created a Revit model (.rvt) that contains only site information, i.e. topography.

I then created 4 separate revit models (.rvt) for various buildings on the site. They are linked into the site model noted above.

Issue:

When I turn on shadows within the primary site model, the buildings do not cast shadows. The faces will change hues depending on the time of day, but shadows are not present. The individual building models cast shadows within their individual models. Site components placed in the primary site model cast shadows.

Do you have any idea why the buildings do not cast shadows and how to fix it?