Anyone have any experience with this? Original fare class was X, did a buy up to PS and now my fare class is G. Called into Delta Customer Service and they said I can't MUA because the original fare class was X. FWIW, folks on Reddit had said they'd had success doing this method in the past. Also, I had called in maybe 10 minutes after doing the buy up on the app so not sure if things need to be reticketed or what's going on.

Any experience with this situation and know what to say to an agent to get into D1?