Your travel reservations are never guaranteed, if the travel provider can sell your trip to someone else for (enough) more money. I wrote recently about Hilton cancelling all summer reservations at a Hawaiian hotel property, leaving guests with few options when the hotel had a chance to sell out to a single group booking. Now a similar situation has happened with Hyatt, though unsurprisingly Hyatt did more for the guests that were bumped.
A customer booked at Alila Ventana Big Sur in September on points for their 25th anniversary found that their reservation was being cancelled by the hotel because the property got a better deal from a group booking.