We were on the Apex March 2023. I made ATD (SD) reservations for 6:00 PM for every night in the Cosmopolitan in my CP long before our sail date. Once we boarded the ship we went directly to the Cosmopolitan to very our reservations. We were politely advised at that time reservations were no longer being honored. Bummer! But we were told if we showed up every evening by 6:00 PM they would hold a table for us. The host allowed us to select a two top in a location we liked. We had the same time, table, wait staff and sommelier every evening. We noticed a lot of available tables when we arrived and left the MDR.
We also have Select Dining (ATD) reservations for 6:00 PM for our October Eclipse and September Edge cruises.