Apple Card unable to be added as payment method under Apple ID

When I go to Settings > Apple ID > Payment & Shipping > Add Payment Method I get the pop-up message below every time. This only happens with my Apple Card. If I select it from the "Found in Wallet" list I get the pop-up, and if I enter the card information from Wallet I get the text in red. I've had this issue for several months with multiple software versions installed on my X. What I've tried so far: removing Apple Card from Wallet and re-adding, signing out of my Apple ID, going to Wallet and selecting "Make Default at Apple" (which doesn't add it to my Apple ID). Has anyone else experienced this? It works with Apple Pay, I just can't use it for any app, iTunes, or subscription purchases.

I've reached out multiple times to Support, and they give me the same run-around. Today I had a scheduled call that lasted 52 minutes. The first Apple advisor put me on hold while he talked to Apple Card support, who said that it is a billing issue. So he transferred me to an Apple billing advisor, who had no information from the previous guy and said he'll transfer me to Apple Card support. I told him that the last advisor said it was related to billing and the Apple Card team can't help, so he put me on hold. After about 15 minutes on hold he hung up and never called back.