So, I just finished my 1 hour phone call with Chase Travel. When I booked Cosmopolitan Hotel at Vegas with Chase EDIT, it said Resort Fee is included. When I got my bill, I saw that it was charged in the bill and Chase's "Mastercard" prepaid credit did not cover it. First I contacted MGM to find out why and they replied that Chase did not pay for the Resort Fee. And then I just finished calling Chase Travel and after a long checking, they said MGM does not allow Resort Fee to be prepaid and you have to pay at check in time. So even though Chase Travel system "clearly" said the Resort Fee of $50 per day is included, it was not. And worst Chase Travel would not just refund it themselves. BTW, because I got the folio from MGM, I knew that Chase Travel charges me $1009 for the room but MGM is only charging Chase $889.

My advice for anyone going to book MGM hotels at Vegas is that make sure you have a print out of your Resort Fee included at check in. And you have to insisted at check in that Resort Fee is included so that they may waive it at the hotel because once you get the room charge on your credit card, Chase Travel won't admit that it's their fault or refund that money.