In most cases importing files from SKP loses the material information if the objects are part of SKP Components (equivalent of Rhino block instances). If all is exploded in SKP prior to import, materials come though OK. I have uploaded 2 sample files for you via Tech Support and happy to discuss more/provide more samples as needed. Just wondering first if you can see/repeat that problem.
Most SKP files use Components so this not working makes it difficult to deal with these files.