I made a reservation in the Maze last week and got the following response:
"We have received your request for a backcountry overnight permit. We are currently unable to request payment of the required fees, due to budget issues tied to the end of the Federal fiscal year on September 30, 2017.
We will send a payment request to you at this email address once we are able to process payments. That will be on or after October 2, 2017. Your dates and campsites will be held under your name. Once we receive payment we will email your permit or a notice to check in to receive it at the district where your trip begins.
If you do not receive an email to pay before your travel begins, note that you will be able to pay the fee and receive your permit at the visitor center in the district where your backcountry trip begins."
I'm not sure what kind of "budget issues" would prevent them from taking your money, but it sounds like for the next week, or maybe longer, permits have to be paid for and picked up at the ranger station.