HDMI 1 (Ultra HD Deep Colour - activated) -> NUC
HDMI 2 (HDMI-CEC) -> Soundbar
HDMI 3 -> XBOX One
I've already connected the NUC to my Soundbar, but this do not solved the problem
Right, that's unusual, working in Windows but not in LE.
The obvious difference between these is the version of libcec, v4.0.1 in LE and v3.0.0 (I believe) in Windows.
Since it's working in Windows you'd have to think it's a libcec problem related to the equipment mix.
Perhaps the best approach is to try and get the attention of the libcec maintainer.
Not sure how to do that, perhaps the Kodi forum would work or maybe logging a github issue will get his attention.
[hr]
I encounter exactly the same issue with a NUC6CAYH Apollo Lake NUC. I've also removed the internal Pulse Eight adapter and installed the external Pulse Eight USB adapter => same issue!
Which gives me the idea that it has to do something with Libreelec + the newer NUC hardware since you confirmed you have no problem when using Kodi on Win10. I didn't try this yet myself.
Maybe we can test ubuntu + Kodi or Openelec to see if this setup has the same behavior?
It gets stranger and stranger.
I wonder what's different between our setups (since mine worked ok)?
My device:
BIOS: revision 29 at adapter install, 38 now.
LE 8.0.1
Connected to Denon AVR-X1200W => Sony KD-X8500C (ARC HDMI port)
I wonder what the NUC is announcing itself as in Windows vs LE, a Recorder or Player device?
In LE it announces as a Recorder device which should be fine, I think there can be 3 recording devices on the cec bus.
Umm .. what's the limit on the total number of cec devices on the cec bus?
I think it's 9, certainly at least 7, sounds like neither of you have that many cec devices.
I know that when I put my old NUC in a setup as a fourth player it didn't work giving symptoms similar to what's described here, I changed it to a announce itself as a recording device and all was ok.
I'm at a loss as to what's causing this, and you'd have to conclude it might not be the NUC hardware as mine is ok .....