This seems to be recurring theme I see being reported for more and more US based cards. It fundamentally stems from the US aquiring bank handling the backend payment infrastructure being scattered across hundreds of smaller banking institutions, the result being that implementation of new payment tech is hard and slow. Former example was how the US only moved to chip + signature whereas many other jurisdictions went with chip + pin.

Anyways, the blocker is likely to be the Payment Services Directive 2 (PSD2) and strong customer authentication (SCA} standard that is the blocker here - being able to authenticate a new retailer or a transaction with a push notification / SMS or other 2nd factor.

I am not based in the US or have direct experience of US cards but I have seen reports that some Citi cards support PSD2 and SCA and maybe some BOA cards, but not all. Modern challenger banks are more likely to have the modern backend systems to support these things out of the box. You probably need to reach out to your card issuer and ask them about PSD2 and SCA support, and moan at them when they shrug their shoulders.

For retailers that demand PSD2 and SCA the process to sign up or make a payment will just appear to fail if you card doesn't support these standards as the call into your card issuer to confirm you are the cardholder doesn't go anywhere. Retailers are frequently loathed to permit transactions that are not PSD2 / SCA authorised as in many jurisdictions they have to take all the risk on those transactions not being paid, whereas PSD2 / SCA authorised are almost risk free from the retailer's point of view.