So, I did a test flight, heading straight west out of Chicago Executive on FL300. Stock aircraft (Cessna Citation Longitude), no ai traffic, AIG traffic folder in community folder removed.
Just north of Des Moines, quite exaclty after 300 nm I got this:
However, the winds did not revert to 225/03 at the same time. They stayed at the more or less correct 270/80 (checked on windy.com) untill just west of Norfolk, some 130 nm further.
I then turned back and flew east. When I reached Des Moines, the clouds were still there. I continued east and would have expected the winds to turn back to 270/80 but - no - they stayed at 225/03. Even when I landed at Des Moines.
Puzzling…