I have now had folks from both American Airlines and Citi executive support reach out to me on this, multiple times, and nobody will take any responsibility for this. It is driving me crazy.
American's person is utterly confused as to the issue. They kept saying that they had even asked coworkers about it and people were telling them that they'd been able to add their Citi Executive Aadvantage cards to "Google Pay." I had to walk them through the differences between Apple Pay, Samsung Pay, and Google Pay/Wallet. We were finally able to get on the same page about being able to add the card to Google Pay to make payments on websites, but still being barred from adding it to Google Wallet for tap to pay in stores. Unfortunately, once we got to that point, they still had no idea what to do or what to tell me.
The latest rep I spoke to from Citi was very generous with her time but started out by telling me something she'd no doubt been handed by someone in IT - that I couldn't add the card to my Google Wallet because I was "using a VPN." Well, even leaving aside how little sense that explanation makes, I was able to point to this thread and say it was quite unlikely that all of the people on this thread with the same issue were also using a VPN. I also pointed out that Citi's own website says none of their Aadvantage cards can be used with Google Pay (technically they mean Google Wallet, but it's not their fault Google has rebranded the tap-to-pay digital wallet product so many times). To her credit, she then said "So that VPN explanation makes no sense, then." Nope, no it doesn't. But she still didn't have any explanation or any fix for it, not surprisingly.

I really cannot believe that in 2024, a major credit card issuer won't allow a line of cards to be used with a major digital wallet. It being an American policy makes no sense, because the American Barclays cards work with Google Wallet just fine. It doesn't make sense as a Citi policy either, because Citi's other cards work with Google Wallet just fine. So WHAT THE HECK. I swear, all it would take is probably two people getting on the phone and realizing that this goes back to some tech limitation from eight years ago that no longer exists, and that they could fix it in five minutes. It is absolutely pathetic that these two major companies can't get their act together and fix it.