Sounds like what used to happen to me with JB...I would see a flight one day and when I went back a few days later it didn't exist anymore...but...when I went on a different computer it was back again.
I also checked ITA software and it is there as well
American Airlines Inc. flight 1596
Dep
New York
Jan 16
7:10 am
Arr
St Maarten
Jan 16
12:22 pm
Duration
4h 12m
Cabin
Economy (V)
Aircraft
Boeing 757