The rules state that the product your going over must have a higher compression and shear strength. Problem is when a compound is drying it will try and shrink. If the product on the subfloor is poor quality then the better quality compound going over the top will cause it to blow.
funny that , had the same thing happen to me the other day. ground workers had put latex on the floor and i mean latex the floor was like putty, i said i'm not fitting on that and site manager said do it you wont get any comebacks. Nothing was going on top of it , it was just to make the floor look better for the people moving in.
