The system is notoriously glitchy. I was able to get a reservation after the time it was posted here that they were sold out. I made a reservation somewhere between ~7:30-7:45am and at the time, all dates were showing as "green" with reservations available. And then minutes later the page was down. It could have sold out just seemed odd.
Editing to add that
Chefs posted on insta ~9:30am ET that reservations were open so that might be a place to ask them directly about availability.