I have run across this issue a few times.
I design a part, then I assign a class with a specific colour. When I render the part, the correct class colour doesnt render properly. I obviously assumed that I didnt assign the class 'deep enough' in the part, but everything seems like it is set properly.
Also, on the attributes, the fill colour shows White with the same-as-class arrow, when in my class menu, the colour is set to blue.
Anyone have any ideas?