!! maybe contaminated paint ??
I had the same problem with fish-eye, after using an epoxy primer I sprayed the lower half of my fuselage with white ppg desothane, to my horror I had up to a dozen spots in a square inch- dumb me I didnt stop at first notice but continued with my three coats, it looked terrible. I cleaned my air filter, used a differant hose, carried any oils and silicone products out of my shop, sanded the paint and started over,second time same results- now Im sick ! I called my supplier and the rep from ppg.This is not my first rodio as Ive painted a dozen vehicles over the last twenty years with good results ! I concluded it was the paint because during the drying time I painted other parts in red with good results. The rep also admitted it could be the paint and sent me another gallon with which I had good results. All this to say it may happen. If you prep and prepare properly and still have bad results contact your rep before you pull out your hair !! Good luck !