I can't take credit for this, but it's buried in one of the other threads about UA's catastrophic new website implementation. I thought I'd repeat it here so no one has to go searching.

If you have itineraries that don't show up in the "My Itineraries" screen:

1. Go to the Mileage Plus page.
2. Click on Request Upgrade under the E-Upgrades section.
3. All your pending itineraries should now be listed. Select the one you want and click on "View Itinerary."

Ta-dah!