Unable to import CAD file

Hi guys, anyone know why some fairly basic rhino scenes (.3dm files) get stuck on 0% when using import CAD?
Is there some known issues with certain scene configurations? I can’s see anything wrong with the scene.
Unreal version 4.20.2
Rhino 6 3dm
materials using layer
no textures, no plugins
no lights no cameras
importing geometry and materials only