Reading that it seems to work on your LE images (i'll test that later), could you tell me if it's enabled by LE specific patches (dts, kernel, kodi, alsa config ?) or should it work on any stock bsp kernel ?
I can only tell that you need to have a proper dtb configuration (like here: arch/arm64/boot/dts/amlogic: modify audio_pin1 and usb parameters for… · kszaq/[email protected] · GitHub) and a working audio driver. I'm not sure whether SPDIF works with mainline kernel.
Would you please compile the latest version of Tvheadend? It has lots of improvments for IPTV networks.
I may look into updating TVHeadend to 4.2.5. If you are asking about TVH 4.3 I don't think I want to push a development version to virtually all TVHeadend users on my builds.