Earlier this year I was on the waitlist for JFK-HEL upgrade for 2 months...they had at least 11 available seats according to expertflyer.com when they said that I'd be put on the waitlist.
The day before the flight there was 3-4 available seats.
No upgrade. Flew home with a 39° fever in economy comfort.
AY Plat status didn't deliver
There was a storm in NYC area the day after, and I bet that some people with a flight for the storm day changed their flight to the day before to secure they'd have a flight, and the rest of the J seats were gone with the wind.
But 8 weeks prior the flight waitlisted. Damn. Still hurts my brain