The autopay reward normally stays listed as $6 under "rewards" until your renewal. At midnight of your payment due date (as listed in your account overview page), all rewards are converted into available funds. Then the billing system uses up available funds first toward your renewal and charges the remaining balance from your credit card if necessary. You may have seen $6 sitting in available funds previously, because the very first autopay reward from your first 90-day cycle is not applied immediately, but credited as available funds and saved toward your first renewal. Therefore the total discounts resulting from autopay on your first few cycles after activation would follow this pattern: $0, $12, $6, $6, $6, etc. (The $12 discount on the 2nd cycle consists of $6 from available funds converted from the very first autopay reward + $6 from the regularly occurring autopay.) That is exactly how it happened in my account and I've seen it reported by others as well.
