My problem was a Micro HDMI plug to HDMI-A socket converter, to convert the pi4 new video interface to fix the cable i had for the old pi3 that runs through my ceiling. Bought this converter off ebay and CEC did not work:-
Micro HDMI To HDMI Adapter Convertor Cable For Amazon Kindle Fire HD 7 8 9 | eBay
So bought this converter from Amazon and CEC now does work:-
UGREEN Micro HDMI to HDMI Adapter, Support 4K, 3D with: Amazon.co.uk: Electronics
So you need a quality MicroHDMI to HDMI converter or CEC might not work.