Originally Posted by
RooFlyer
Only thing I can think of is that the '4 day prior' booking window for E pax is 4 x 24 hour periods before the flight time, rather than 4 calendar days. Is this the case?
Yes, that is exactly why -- it is measured on a 24 hour clock. So if your flight is at 4:30 AM, your upgrade booking window will open at 4:30 AM the prescribed number of days before your flight.