There is a substance in some paints and other finishes (can't remember the right name) that doesn't agree with polys. It's a soapy substance that can be found in some sealers/primers to help lubricate the scuff-sanding process. This is all pretty sketchy based on a conversation that I had some twenty years ago with a lifelong finish guy. I'd suggest a test run on scrap. And I don't even know what the reaction would be.
