Originally Posted by SpaethCo

Does it actually allow changes, or does it appear to allow changes and throw an error if you actually try and commit?

The really fun situation is when you cancel with the airline and your money just gets stuck in limbo, which is the case with AA and a few other airlines. You can’t use the credit to rebook directly with AA because it’s “owned” by the booking agent, so then you get to track down someone at Expedia / Orbitz / cxLoyalty / Hopper / whoever who will look past your “not cancelled on their side” booking and dig in to the airline interface to see that credit so you can maybe apply it to a future flight. (Some unlucky souls on Reddit gave up after trying for > 24 hours in total call time) In general you can cancel on Delta and United and still have the funds available for use for flights booked directly with those airlines, but that scenario is not universal for all airlines in the portal, and doesn’t even always work with all flights on Delta or United depending on if special fare codes are booked.