I mainly fly UA and DL so I am more familiar with their intricacies but I have a flight in July I am looking to upfare from Economy to Premium Economy as it is less than the price of purchasing the upgrades. I have done this in the past on UA and DL via their website by making a flight change and just selecting the higher cabin. I have been running into two different issues with this:

• At first it wasn't even showing me my existing flights AT ALL. This seems to have resolved itself since I saw it last (4/9/2026)
• Now that that seems to be "working" it isn't showing me the Premium Economy options for my flights, just business.
• There is definitely Premium Economy space as I could book it as a new itinerary.

I guess as a last-ditch effort I could just cancel it, get a credit and then re-book into premium economy but that seems kind of....dumb. Am I missing something here?