I've got a killer high-tack and high coat-weight adhesive vinyl made for me by Drytac. It has double the amount of adhesive coating than a standard film and the adhesive sticks like grim death to just about anything. I've got users who put this on powder-coated metals and (knock-on-wood) no issues.
If this worked before and doesn't work now, then you likely have a bad batch of material...but if you want to test out my stuff, please don't hesitate.