My comments above relating to deb installers were on a Raspberry Pi as a TVHeadend Server. not on the Libreelec client.
I gave up on TV Headend , way too many problems.
Even if I had resolved half of them, it was still full of quirks, unstable, flaky recording, poor documentation, etc.
I installed NextPVR quicker and easier than I expected. It seemed more logical than my first attempt for some reason. I kept looking to see if there was more to configure but then installed the client in Libreelec and boom , it just works!
Only problem is getting guide data in NextPVR as apparently it will not use Over the Air listings for what reason I fail to understand. I do believe that is where the listings came from in TVheadend.