Most Popular Flush for 2018 Audi Q7

The rails looks and functions great on my 16 Mini Countryman. However, when I drive over 35mph, there is a sharp hissing sound coming from the rails. these rails are supposed to be aerodynamically enough to eliminate sounds. I tried switching the front to rear and same issue. I went as far as taping any voids to see if that would help. Nothing works.