Problems getting correct information from step file

Hi,

I try to extract information from step file like names and colors but I simply don't know when to take the label itsself (instance) or when to use the referredLabel (product).

I made a test in FreeCAD with 5 different colored boxes and exported to step. See attached screenshot CadAssistant.png (expected result!). When opening again with FreeCAD, the instance color is not used. Only the referredLabel color ist shown. When opening with Fougue/Mayo it results in the same.

I debugged my c++ code and found out that XCAFDoc_ShapeTool::IsReference(label) always returns true and thus the referredLabel color is used. But this does not work at all. The OCC example step is all over yellow as this seems to be the default color when no other color information is available.

However when I'm using OpenCascades included V3d_View then everything has the right colors. V3d_View and Cad-Assistant seem to handle things differently? But I don't know how and where. The same is with the names.

So my question is what the difference is there and what am I doing wrong?

I have attached some screenshots and my test step file with 5 boxes that I used with Cad Assistant, Mayo and my own viewer(s).