I had the same situation when looking to book at a Hampton Inn in Pennsylvania. Even more annoyingly, when I was searching for hotels using points, this HI came up on the matrix and listed 30K points. When I went to reserve the room, the screen said the points only rooms were sold out but I could book a room for cash.
I figured this was an IT glitch and posed the question through Chat while on the website. The Chat operator checked and said all the award rooms were sold out. I called the Diamond Desk and that agent as able to book using my points. n
