At the moment the Classification Manager for Revit doesn't work with parts because it cannot create the required parameters in Parts created in Revit. I discovered this on a project we were the facade contractor providing the SFS backing wall out to the Terracotta Rainscreen panels. I created the Terracotta panels as Generic models, so there was no problem in classifying these. However, I created the rest of the wall buildup using a single compound wall. We were required to classify the SFS and the Insulation layers of the compound wall as their separate "Uniclass 2015 " classifications, so I made the walls parts, excluded the layers I didn't need and merged the parts that were the same element. I then tried to use the classification tool to classify the elements of the walls. No matter what I tried, I couldn't get the classification manager to work on the Part elements within my model. In the end, I had to re-model the walls as separate walls, one for the SFS and one for the Insulation layer.