I attached a screenshot of my CEC setting but I believe it's not the cause of your problem.On my Toshiba TV, it was 'MBOX' in the past (many builds back) but it is now shown 'Kodi'. Also if you don't find it on your TV CEC settings, reboot of your Beelink M18 with your TV turned on should help. You need to let your TV recognize your Beelink M18.
As far as I know, there's been an update to the CEC code in the latest build.
Thanks! I tried everything, but sadly it's not working, only with earlier builds & under android.