If you attempt to add the same card more than 5 times in a 24 hour period, it’ll be blocked.
When you attempt to add a card to the device, your iPhone sends information on your iPhone to the Payment Network Operator (PNO) Visa and if they approve then information is forwarded to your bank. The PNO does the validation check, and it appears they are getting the information because of the invalid notification. If card is validated by Visa, the data is sent to the bank for final verification and approval.
If the bank declines, you receive a notification. If they approve, they typically use a Two Factor Authentication text message to verify the device is yours etc. If the response to 2FA is correct the bank issues a dynamic encrypted token, which represents your card. The token is sent to Apple servers and then installed in the Secure Element.
Both the PNO and your bank employ algorithms to evaluate the risk potential. Adding the card, is not something Apple participates in beyond the pure mechanics of once the bank approves, Apple adds the encrypted token representing your card, to your device.
Information Apple provides to the PNO and the bank are disclosed in several support documents Apple publishes. I’ve linked them below. The entire process is anonymous to Apple as part of their privacy and security protocols.
My best guess is the communication is breaking down between the PNO and the bank. Ask the bank if they are receiving the data from the PNO (Visa)?
I’m happy to answer any additional questions you have.
Apple Pay security and privacy overview - Apple Support
Card provisioning security overview - Apple Support
Apple Pay component security - Apple Support
Apple Pay Wallet Terms and Conditions
Adding credit or debit cards to Apple Pay - Apple Support