Pattern I've now seen on four different cards and I'd like to know if it's universal or if I'm doing something wrong.
First charge on a new subscription: fine, always. Second charge, thirty days later: fine, usually. Third charge: dead, roughly half the time.
It is not the balance. It is not the amount, which is identical every month by definition. What I think is happening is that the first charge is a fresh authorisation and the later ones come through as a merchant-initiated transaction against a stored credential, and something in that flow stops matching. IME the response looks like this:
auth_type: MIT / recurring
result: declined
reason: 14 - invalid card number
Reason 14 on a card number that worked twice already is nonsense on its face, which is what makes me think it's the stored-credential handshake rather than the card.
Anyone actually running monthly rebills past six months on one card? Which one, and did you do anything specific to keep it alive?