Originally Posted by wyowindworks
If I was in your position I would try to reconstruct the problem. I'd shot a scrap with you plug paint and let it cure. Then I'd apply the sealer to one half of the sample and apply the release to the whole sample. Then do a simple layup with your gel-coat and a molding resin on the sample. Let it cure and peel it off. If the side without the sealer sticks then you know that not using the sealer is the issue.
This is very good advice! However, it takes a bit of effort but it will tell you where you're going wrong in all likelyhood.
New plugs and new moulds are always much riskier than seasoned moulds, They are prone to outgassing, porosity, lack of complete cure etc. If there's any stage of mouldmaking to take great care with it's new moulds!
Don't give up! It's not an easy thing to learn, but the payback in personal gratification is well worth it!