A full JFK-MXP J cabin is not unusual. My wife and I flew JFK-MXP in June and were waitlisted for upgrades. Ultimately no one was upgraded. 21 J seats were open when I booked 5 months prior, all were filled 10 days out. At the time I checked other days and very few, if any, J seats were open on that flight.
It was the first time I missed an international upgrade.