Hey there! Sorry to hear you're experiencing an issue with adding your card into the saved payment information. Sometimes the payment gateway does not allow you to save a card until you've made a purchase with it. What has worked for me, and I would suggest trying, is not saving it until you've used it to place an order.
If you've already placed orders, I would suggest emailing our support team at firstname.lastname@example.org. They can take that information to the payment gateway and make sure it didn't put a security lock or anything else on the card. Hope that helps!