I have the latest firware. HDMI CEC is enabled and has been working since I bought the WD TV Live SMP last year. When I pressed the power on button on the WD TV Live SMP remote, my Sony Sound Bar came on and switched to the HDMI port the WD is connected to. And pressing 1 or 2 on the WD remote raised or lowered the volume on the soundbar.
This stopped working recently. I have reset the device back to factory default and renabled HDMI CEC but this didn’t fix it. Pressing the reset button on the bottom of the WD didn’t fix it either.