Does the list of hotels for the chosen dates always show all HRS partner hotels?
No. The number of hotels always varies because you are shown only those you can book immediately. It might be two hotels, it might be 300. It all depends on how many of them are currently fully-occupied. You are therefore shown only those (as well as all the important hotel information) that want bookings – and you can book them directly at the cheapest current guaranteed HRS price.