First of all, I have nev er painted a mold before, but that shouln't matter, if it is thouroghly waxed over.  The problem I think is that PVA has a solvent that keeps the mold release in a liquid state, untill it is sprayed or painted onto a surface.  Then the solvent evaporates and leaves behind it the green mold release film.  If you are applying this solvent onto a previously waxed mold, the solvent will liquify the wax mold release underneath it and you will have a chaotic mold release situation.  Stick with one or the other, and that should do it.  I noticed you mentioned a coat of epoxy before glassing.  Very good.  Polyester has solvent that breaks down wax mold release.  This first coat of epoxy; is it sprayed or brushed? PVA is basically a very thin layer of wax.  It can be broken easily by a sqeegee or even a brush.  Make sure this first coat of epoxy is sprayed on delicately.  Give the epoxy plenty of time to completey cure before glassing over it.