Is there a Achievement Bug?

[Magic Breeze]

I play now more hours and end every single map with 3 silver stars at least. Means this not that all maps be finished with 100% core HP? I try to get the achivement Munchkin where you have to have on every single map 100% core hp. If the 3 stars not mean that i have 100 core HP, where i can find this information what map is missed???? Thanks for any help