Hi - I'm getting the following error trying to login for my flight back from New York JFK to London Heathrow at 19:45 tomorrow (31st October), arriving in London 06:45 (1st November).

• We’re sorry, we cannot complete online check-in for your flight on this occasion.Please proceed to the airport with your required documentation (including any vaccination and Covid test certificates that are necessary) to check-in and collect your boarding pass.

I am only flying back for the weekend for some appointments and therefore need to be on that flight. I specifically fast tracked my TSA pre-check approval so that I would have it for this flight. I added the "Known Passenger" details a month ago but now I am getting an error. There is also a notification saying "one of your destinations requires passport scanning". Please advise