I don't know 'Super Flat' belongs to what base. But I had a similar problem when I used acrylic Gunze flat clear, especially when I didn't thin it enough. Now I use Humbol enamel flat and thin it with 1part thinner(i.e. 1 part paint with 1part thinner) and the result is very good.
P.S. Make sure you have good ventilation and have a respirator when airbrush enamel paint.