The part itself or the paint is contaminated.
Silicone is usually the culprit.
Wiping a mixing stick with a rag that was used for applying Armor All will ruin your paint. Even half a day after Armor All, silicone spray or oil is vaporized, residual will trickle down on your work surface. Air powered tools (impact wrenches, etc) actually vaporize lubricating oil as they are used.
Since you already have paint on the part and holes (voids) have formed, you'll have no choice than to sand smooth.
Are you using a mild cleaning solvent BEFORE spray painting? Not thinner or reducer, they will soften the base.
whizzerick
