Same annoyance for me. The air is coming from below, up and around the gas tank. I am on my third windscreen, but haven't messed with fork deflectors or other devices.
I do have those frame heat shields (heat deflectors) that mount under my seat. But these don't stop the up-draft.
I just finished a 4k (10 day) run to Sturgis and back, and had lots of time to mess with air flow. My leg positions did change things up, but did not cure the breeze. I was mostly interstate cruising and maintained a quick pace with two other buddies. Quite often we were hammered-down at 80-85mph trying to knock the boredom out of Missouri and later, Nebraska.
I too, noticed a lot of up-draft crossing my ears and my straps for my half-helmet. All of it traced to down beside my gas tank.
I haven't found a good solution; but remain grateful that I am enjoying my Harley, and simply accept that it is what it is.