This has happened to me the past two days. Yesterday I called at 8:15 (90 days out) for dinner at Crystal Palace. The latest I could get was 4:30. This was a party of 9 so I figured that had something to do with it. This morning I called at 7:15 for the FDP at Hollywood and Vine (again 90 days out). It was only for the 5 of us so I was pretty confident in getting close to the time I wanted (6:15). Again, the latest I could get was 4:30! I asked the CM how that could be and she said that they only block off early times for the FDP. Out of curiosity, I asked her if I just wanted to book H&V without the FDP, what time could I get. She said the last seating for the restaurant was 6:00. Then she said that MGM must be closing early that night. So I think this supports the theory that was offered here that until the official hours are posted, they assume that all parks will close early and the PS times will reflect that. I plan to call back once the June hours are released.
Mike