I suspect some issues with the primer, perhaps for sitting that long or temp that it was kept. In my experience even somewhat poorly prepped piece sprayed, it would not flake off that easy.
My prep involves scuffing it with a maroon scotch brite, wash it with soap in somewhat warm water and then clean it with acetone. when sprayed is rock hard. I have had overspray on parts/area that had no prep done, dirty and probably somewhat oily and yet I have to work it to get it clean.
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying