I've noticed when claying that to get some spots out, you have to clay until the surface is smooth, and then continue claying some more. I wonder if I am removing bits of clearcoat to do this. I had this problem on a black car where after a while, I started to get a haze on the high spots of the clearcoat. It looks like when you put fine sandpaper to the paint, and it takes off the high points of the orange peel.