I went to check in for my return flight today and it was completely gone. The confirmation number returned nothing, no itinerary existed in my MP account, and, of course, I could not check in for my flight. My assistant had to spend nearly 2 hours on the phone with UA getting it corrected. When I got the itinerary restored I lost my upgrade that had cleared at the ~96 hour mark and no longer show up on the upgrade list.

The same thing happened to my wife with her itinerary/return from EZE last week.