We found two causes, potato chip grease and lotion from assemblers hands. The company asked that the snacking on-line stop and everyone wore thin cotton gloves. The fisheyes stopped. Hand lotion, wax, grease, oil, spray lubricants, diesel smoke, silicone, can all be culprits. One of the problems areas where I see a lot of wax is in the refinishing of furniture.
Many strippers contain wax.
This wax is used to hold the stripping solvents on the part long enough to take off the finish. Strippers often leave a waxy residue you can feel. If you don't clean off the part with solvent prior to coating, the wax will cause fisheyes. This additive is available from your finish supplier and will decrease the surface tension of the finish and let it stick over the contamination. This is only a Band-Aid to get you through production until the problem can be solved.