They are showing on excursion page for Carnival Legend stops on October 30, 2022 and January 8, 2023. They were sold out on day they were listed. Who knows what system is used to make them available on any particular cruise? Maybe reserved by another ship (Carnival Freedom) also scheduled on your date had them only available for their passengers?
The Mardi Gras is also scheduled on our stopover dates. Only a few cabanas for so many thousands of passengers, they may be alternating availability. Mardi Gras is also scheduled at same time as the Legend's stop in January 19, 2023.