I was having problems with a mileage upgraded reservation for 2 weeks in that I could not see it. Webservices wrote back and said it was due to web server capacity. All my non-upgraded reservations were and are viewable.
Today I checked one more time... I clicked on View and it was followed by some bold red print that said something about "deleting reservation."
It's gone! I can't pull it up manually either by name, flight number, etc.