Z30 slope sometimes wonky?

On occasion, my z30 slope adjustment seems broken or im not understanding if it is adding wind/weather factors. I have it paired with s50 and premium maps subscription. 

On many times, i would be staring at an obviously downhill flag and the range finder would have an up arrow and indicate it is playing a yard longer than the laser measure and vice versa. Not a gps or wrong hole issue. Is there something else it is factoring that isnt in the documentation? I know if its paired to s70 it could do wind. But I just have the s50.