Spraying Minwax Polycrylic, dries with tiny bubbles

I have attempted to spray a fourth coat of Minwax’s Polycrylic after allowing the previous coat to dry for a week. This is the third try on putting on a final coat. Each time, the finish goes on wet and levels out perfectly. About 30-60 minutes later after it dries, it develops very small bubbles which affect the glossy sheen. The surface feels smooth and flat but the tiny micro bubbles in the finish make it lose it’s sheen.
After each try, I let the finish cure and sand it back using 220 grit before attempting another coat. I have tried putting the finish on a little thicker, but that did not work. Not sure what is causing this issue. I did not have this issues with the previous coats. This is being sprayed with a Fuji Mini Mate 3 (1.3mm tip) at a temperature of around 60 degrees F. Under the existing three coats of polycrylic are two coats of primer and two coats of an exterior flat latex paint.
Please let me know if you have any ideas on what may be causing this issue.

Thanks Gregg

I painted cars in another life and the tiny bubbles you are talking about resulted from the top of the paint skimming over too fast and the solvent continuing to escape from the finish and forcing its way through the surface of the finish. If you sand it then you have tiny pinholes which will then create new bubbles in the fresh later of finish. Once you get the bubbles let it dry and sand the entire layer off then try another coat.

Jack