I'm running PM 4.6 and NX2 2.1.1 on Vista. In PMI set color class on a some photos from a shoot. In NX2, I selected the photos with the color set and applied a batch setting to adjust exposure. Back over in PM, I can't change the color class. I even tried closing NX2 to make sure that it wasn't interfering. I can, however, change the star rating. I have also followed the instructions in the help to set the preferences for working with NX2. to I'll be happy to send you one of the problem NEF files if that would help.
Danny