Oil- and latex-based paints can't go on top of each other; the compounds don't bind, which means you'll get air bubbles in the top layer of paint. You Painted Over Wet Paint or Primer Not waiting ...

Blisters or bubbles appear when a layer of paint does not adhere perfectly to its underlying surface, known as the substrate. As the new film of paint dries and pulls away, pockets of air or water ...