We're having an issue performing a $0.00 auth with a Discover card. There is no AVS response (which our system uses for fraud prevention) even though we're supplying a valid billing_address object. This is the first time we're seeing this lack of an AVS response, and the only difference in this case is that it's a Discover card. The transaction is fine otherwise.
Can you please provide some input regarding the potential cause of this issue, and any troubleshooting avenues that we may want to explore? The cardholder has checked with their bank who has ensured them that the card is fine.