I have the same problem with my recently purchased camera Hikvision DS-2CD2432F-iW, purchased especially for the PIR sensor, but I could not make it to record to a QNAP NVR.
Camera has the latest firmware V5.4.5 build 170123.
I tried for "Record Schedule" all possibilities: Motion, Alarm, Motion | Alarm, Motion & Alarm, Event.
On the "Basic Event" -> "PIR Alarm" -> Linkage Method, I tried all the check boxes but all I've seen to be functioning is the "Audible Warning" and to trigger an Alarm Output on A>1.
Using "ONVIF Device Manager", I can see in the Events when the PIR detects motion that it only triggers an event "RelayToken:AlarmOut_1" goes Active. That makes me think that all the PIR can do is to Trigger the Out Relay and the audible siren, but nothing more (in fact it is true that I haven't tried email or FTP/NAS) but I don't see in "ONVIF Device Manager" that it would try to do any more.