Exporting from Revit with Linked AutoCAD

I am using "Bentley LumenRT 16.01" aka "lumrt16013066en.exe" to export from a Revit 2015 model that has other Revit Models Linked, and one of them has AutoCAD 3D DWG's linked into In-Place Families.

Only some of the AutoCAD 3D Objects get exported to LumenRT.

Is there any reason or known limitation in this workflow?

How would we otherwise get the 3D DWG Model objects into that LumenRT session/model so we can see everything and start to apply materials where needed? 

PS... When you select "help" in LumenRT it goes to a dead link...