PM with Delta Plat Amex
2/9 JFK-LAX on a T fare. Upgraded to C+ shortly after booking. Was 20/39 for 17 seats.
2/13 LAX-JFK on a X fare. Upgraded to C+ shortly after booking. Was 19/47 for 4 seats. However, around 30-45 min before boarding, all 4 seats disappeared and no one cleared from the upgrade list.