Wicked paint reaction - why?

That base looks insanely heavy.

I don't think this has so much to do with wax/ grease remover as it does flash time in between base coats and how heavy each coat is.

Wax and grease remover usually flashes within enough time to clean/ check the gun and mix base. By the time you've gone over the car with a tac cloth and you have the paint in the gun, that wax/ grease remover is gone.

Look at the film thickness on those ridges. That tells you right there what the problem was. Solvents from prior base coats trying to flash, under a new film of heavy base.

Take your time with base. It's all about even color. Better off with light coats, then light to medium coats, multiple times.

I clear in the same session, but I go around the car after 15 min with the last of the base in the gun, nib any dust with 1000 and blend those spots, come back in with the clear gun in one hand and a tac cloth in the other, hit the entire car before clearing. I also tac lower areas during base to keep from dust buildup. Shoot the roof, come back in, tac off the hood and decklid. I go through about 3 tac cloths with every complete paint job. Night and day quality of layout when it comes to metallics, too.