What is it?
A progressive loss of adhesion between dry paint film and it's substrate.
Poor surface preparation.
Chalky/Glossy surface.
Incompatibility of coats.
Poor curing of undercoat.
Rub down the area to the prime flat until surface smooth.
Repaint the surface with proper painting system.
Proper surface preparation.
Select right painting system
Remove loose dust,gloss & paint.
Cure well between the coats.