3 weeks ago was flying from EU to US in J (full fare) and decided to try and upgrade to F. Had no status at the time (this segment would complete the platinum fast track for me) and asked at the airport to be put on the list to upgrade with miles (25k). I was first on the list and it cleared a bit before boarding. At the gate the GA confirmed that I was upgrading with miles and I boarded in F. Was actually a fantastic flight, with great service.
As as of now they haven't been pulled. I've received credit for the flight and it shows me in J. How long out does it take to catch up?