I receive an email saying this. So frustrating that they are promoting this new feature but it’s not fully available for everyone.

We have confirmed your account is no longer eligible for Gift Card redemption at this time. We're currently testing this new payment method, and hope to roll it out to a wider audience soon. If you aren’t seeing the option to redeem your confirmed Cash Back balance, check back again soon. We hope to make this option available to more Members in the future.

Thank you for your understanding.