The non-prepaid FHR bookings should be eligible; I would push back on this(see the first thread below). The prepaid FHR bookings are always problematic and it is difficult to impossible to get Hilton to credit. The Hotel Collection (THC) prepaid booking always show as Expedia and are not eligible.

A couple of relevant threads in the Amex forum:
Online (but not prepaid) FHR booking for Conrad showing up as Expedia

Report chain hotel rewards or benefits on PREPAID FHR and THC stays.