Ya it's pretty strange, at highway speed, I lift my visor and the wind slams it shut which tells me that the turbulence caused by the winscreen is right at the top of my helmet. How tall are you, I'm 5'11".
I'm pretty sure I know what's happening, the wind is coming back to fill the voi from behind the screen, back draft I guess. No issues though I'm sure I'll figure it out. I may be that guy where the laminar lip works for.
I do have to admit that I was pretty apprehensive about adding the roadster screen but I like what it provides. All I wanted was a little pressure off the Chest but still have the wind around my head. I wear a full face on long trips so I have the ability to control my wind. I'll probably never ride without one again.