Hi, just an update. I have raspi4.
In my old Sony Bravia CEC worked with libreelec 9.8 and I didn't have to do anything. When I replaced my tv with Samsung AU9070 CEC stopped. It was about the same time I upgraded from 9.8 to 10.0. couldn't figure out if it was a tv issue or libreelec.
All I changed to get it working was move the microhdmi next to the charging port on raspi4. Point to note, I used a really cheap microhdmi adapter and it still worked..