In the past, purchases I made with my American Express card would show up in the iPhone's Wallet. But now the transaction history is empty, even though I've made a number of purchases in the past few days.

I updated to iOS 14 last week. I don't know if this is when the problem started, as I don't check Wallet very often. Today is probably the first time I looked at it in a couple of weeks.

For some of the cards in my Wallet, Settings->Transactions says

Transactions shown are purchases made with this iPhone.

But it doesn't say that for the AmEx card. It just says "No transactions are available". I haven't made any purchases with the phone in a week or so, so I can't tell if they would show up or not.

I do have "Show History" enabled.

UPDATE:

I made an Apple Pay purchase today, and it shows up in the Wallet. So it seems that AmEx is like the other cards, only showing purchases made with the phone instead of all purchases.

Is this a recent change to the Wallet app?