DIAGNOSIS HDMI-CEC communication is not established or is disabled on one device.
FIX First, enable HDMI Control on the YAS-209. Press and hold Volume Down and Program on the soundbar remote for 5 seconds until the display shows HDMI Ctrl On. Then power cycle both TV and soundbar.
IF THAT DIDN'T WORK The issue is likely the TV's CEC setting. Ensure it is enabled in your TV's sound or external device settings. The HDMI cable must also support CEC; try a different high-speed cable.
HEADS UP Some TV brands have spotty CEC implementation. Samsung and LG are most reliable. Vizio and older Sony TVs often have issues. You may need to use the soundbar remote.