This applies to the Intel NUC6CAYH (and possibly other models too?).
Update to Intel’s latest HDMI firmware as DTS-HD or Dolby TrueHD audio formats did not work “out of the box” in passthrough mode if connecting to a HDMI 2.0 capable amplifier.
Unfortunately, the firmware update can only be applied via Windows so download and temporarily install a demo version of the operating system - but do this after updating to the latest version of the BIOS and stick to its default settings.
Then install the latest LibreELEC 9.2.2 release and all should be OK .
The only problem I still have – that hasn’t been fixed by the LibreELEC guys in 9.2.2 – is with the projectM visualization addon. It’s impossible to change preset packs. They can be selected but the visualization displayed doesn’t change. It is permanently stuck on the projectM default pack. Any ideas to sort this out would be much appreciated. It would also help to cheer up 21 days of corona virus lockdown time here in South Africa ??