Invalid Shipping Address

This morning I tried to use ApplePay on a website. After I double-clicked on the iPhone to complete the transaction, iPhone reported the transaction failed, and the website reported "invalid address."

Attached is a screenshot of my phone Settings➜Wallet & ApplePay➜Shipping Address.

I have hidden identifying information.

You'll note that the only difference between these two addresses is "United States" vs "USA." The second (the one labeled "My Home") is from Contacts. When I checked the shipping address associated with my Apple ID on my Mac, it was the same as the "other" address.

When I tapped on the address that matches my contact, the text turned red and, under the "My home" label it replaced my address with INVALID ADDRESS.

I don't know if any of this is related to the rejection of ApplePay on the vendor's website.

• Address with the card issuer is the same, except that the card issuer also does not have a field for country.
• The website did not have a field for country.
• I have not had this issue before today.
• I have not updated my address with my bank, Apple, or ApplePay since April of last year.

Perhaps notably, when entering my address initially I did not include the ZIP+4 extension (because I find 90% of vendor websites won't recognize ZIP+4 as a valid ZIP code) but the website suggested the ZIP+4 as a "better" address, so that's what I was using on the vendor website. The vendor website did not have a field for country.

Any ideas what's going on here?