bingo, Do you have some flying time on the paint job? When I painted over ultra-coat, it generally worked fine except around the cowl where it rubbed the finish. The paint rubbed off. Every place else had no trouble. I fixed it by using some red ultracoat where the cowl fit on the fuse. This was a 60 sized mustang. I used rustoleum and the nice thing was that when wrinkles showed up (hot in Texas) I could reshrink the ultracoat by laying down a white T-shirt and ironing over that. Just dont let the T-shirt move around or it might smear the paint. But it shrank the ultracoat without cracking any paint or any deformations.
Edwin