I have confirmed the function is enabled, but the screen does not blank when the vehicle is in motion.  When the forklift is first switched on the screen quickly displays a message regards the screen being disabled but then comes back to normal – I  suspect this is due to the vibration caused when the vehicle is first started.
 
The VRC is not detecting the VRC motion.
I used the IST settings function to monitor the motion detection using the visualiser.  When the forklift was first started up there was some motion detected from the vibration, however while the forklift was being driven backwards and forwards there was no motion being detected.