UPDATE: I was able to resolve this though a number of emails and phone calls. See update below.
I am running into an issue with Hyatt blacking out award nights at the Park Hyatt Buenos Aires. It is unclear if they are actually holding back rooms or doing some wacky practices in what rooms are available for award reservations.
I will be in Buenos Aires December 24-27. Granted this is over Christmas, so I expect there to be higher demand. I was able to book the first night on Points + Cash. However, the 25th and 26th are unavailable to book with Points, Points + Cash, or with my Chase Visa Award Nights that I earned through my sign up bonus.