Chris beyond what I sent for comments by email here is some other thoughts...what some have done when having problems like this is to seal, prime, paint as normal but wash the lure with denatured alcohol while wearing gloves then after drying hit the lure with what's called a "scratchcoat" using a coat of krylon or fixative type spray to set a base for the clear. This allows you to put a layer on which can be then "scratched" with fine sandpaper to allow the topcoat to bind to below. You'll find alot of paints have some aluminum flake in them which doesn't take well to a top coat. Some paints are very slippery when dry...gloss makes hardness. Once the lure is sealed and preferably even before that, gloves are an absolute must. Finger oils can cause all kinds of problems, soaps, lotions (i know this one firsthand) all kinds of stuff can cause problems like this.
The higher the gloss the harder the finish and the harder to make something stick to it. This is true of all coatings.
How old was the urethane?
