I imagine you’d need to post logs to allow a closer look at the issue.
Sounds like you’re banging your head off the wall trying to get CEC working. No doubt at this stage your HDMI cables are up to the job and you’ve swapped them in and out to verify this.
Next I’d look at any other peripherals that may be attached that are causing a possible conflict: All HDMI peripherals must allow HDMI pass through. Again the most simplest of setups first to try and rule this in or out.
Finally I’d look at the TV you are using. Have you tried an alternative TV to see if you can replicate or rule out the issue. Again I’ve no doubt you’ve read this simple checklist but I’ll include the link for others who may stumble across this thread https://www.howtogeek.com/207186/how-to-…you-should/amp/
Ironically the reason you may not see a lot of posts on the web concerning CEC issues is that possibly users just get it to work or maybe users just don’t use it.