I also posted this in Kodi forums:
I can only pause/resume but not ff/rew within timeshift buffer. When playing recordings I can ff/rew. The same behavior with Kodi 15.1, 15.2 RC2, 16a3 on a Mac. Timeshift On-Demand is unchecked. Any ideas ?
EDIT: tried on Windows, same behaviour
Running tvheadend 4.1-459 on ubuntu 14.04
EDIT 2: tried 4.1.373 on Synology DS210j and ff/rew works. So it is not Kodi related.
I double checked both Synology and Ubuntu configs, and couldn't find any differences. Would like to switch from DS210j as it is getting old and slow now.
EDIT: solved it thanks to negge from kodi forums !
ff/rew doesn't work on channels without EPG data