I have recently done the same. Had 5 nights booked on points at the Waldorf Palm Dubai over Christmas, but much preferred the NYE 5 nights as they were the more expensive nights in Dubai for our trip. Kept checking and they came up a few weeks ago, excitedly I edited the original points reservation and selected the new dates including the 31st December only to get the confirmation and realise it was now non refundable.

We really are hardwired just to think all points bookings are flexible and Hilton need to get onto this as it’s another devaluation of points and more hotels are doing it.