Well, this is interesting! I am going 08/08-08/17 and also couldn't get a PS later than 5:30ish at MGM, although I was able to get later ones at Epcot WS on two different nights. I had heard it was tough going this year and I called late, only last week, so I didn't think too much of it. What has my curiousity though, is this. When I was booking the PS for 50's Primetime and she told me the latest one was for 5:30, she said that was the latest seating because the park was closing early that night. Being the anal person that I am, I had a color-coded sheet in front of me with park closing times reflecting it being open until 9. So when I said I was confused and had checked the times before planning for MGM that date, she seemed hesitant and said there must just be nothing available after 5:30 then. I thought it strange then since she'd said it was closing early so confidently a moment before -- now this thread has me panicked that they might be contemplating changing the park hours to earlier!