It looks like MGM and Chase Travel may have fixed the issue with charging your Resort Fee at check in. Last month when I booked Cosmopolitan, the Resort Fee is included was not shown after you book. It was only showing under price details when you are booking. And when I was entering the MGM confirmation number on MGM site, it shows that I have a balance of the resort fee. This was even before I got there. When I got there to check in, they also said the room was paid but not the resort fee.

I just booked Bellagio last night and Resort Fee included is now clearly showing after you booked. And when I entered the MGM confirmation number on MGM site, it shows $0.00 balance. I think they finally got it right.