I do remember doing a PNC on glossy paper and I cut on the glossy side. I didn't have a problem. I am not sure what weight the cardstock was, but it is thicker than your normal cardstock. If I remember correctly, it was not a detail cut but maybe a scallop edge with holes. It was several years ago and my memory is fading. LOL. If I remember correctly, I also used a slower speed (this was at a time that I didn't not crank up my speed because I had a fear of high speed). I would think that a multipass would work to cut through the top layer of "gloss" and then the second cut would cut the rest of the way through.
I would check the blade. I would think that having a sharp blade would be important on getting a clean cut on the glossy.