Just had an Email regarding a Hotels.com security breach, where some account holders info was accessed between 26-30th April 2017
The email mentions that some of that information could have been your earned reward nights, usernames or passwords, name and address They state that payment info was not compromised apart from the last 4 digits from a saved payment card
So it seems that Reward nights may have gone missing from members accounts and Hotels.com will restore them, if they can verify that they were removed by someone other than yourself.
Get changing your passwords and check your reward nights are still showing as they should. If not, contact Hotels.com and they should be able to sort you out.
Full email below