Do your cards have two-factor authentication set up?
This warning comes up when purchasing Sagrada Familia tickets:
Important note: To pay by card, as per current EU regulations, you must have the two-factor authentication system activated. If you don’t, please contact your bank before making your purchase.
Read this about two-factor authentication:
https://www.investopedia.com/terms/c/credit-card-authentication.asp
Multi-factor authentication, sometimes called two-factor authentication, provides an extra layer of security to online and mobile transactions by requiring more than one authentication step. For example, a customer might type in their name and password, after which the company at the other end will send a one-time code to their cell phone, which they'll then need to type in to obtain access to the site. Multi-factor authentication is often used by banks and other businesses for online transactions including online bill-paying.