C4D not including certain Soildworks .sldasm and .sldprt files that are within a larger .sldasm file

I have a large .sldasm file that contains other .sldasm files.  Basically, its a huge truck with many parts.  When I open the .sldasm file in C4D much of the parts are missing.  I really don’t want to use .vrml because it doesn’t maintain the mating structure.  This model has thousands of layers and parts.  I want to understand why c4D opens some parts and assemblies in this file but not others.  Any thoughts?  I will try to attach a screen shot.  I can’t share the file because it’s proprietary.