I have a ... kind of ... similar issue that I have had to work around - but with video as well as audio.
My setup is an Odroid H2 (Gemini Lake J4105 micro x86 system-on-a-board thing) connected to a Yamaha RX-V485 receiver connected to a Samsung RU7400 TV.
When I use my Logitech Harmony remote to power on all three devices at once the TV doesn't register any input from the Odroid.
The Odroid *is* up and running - I can SSH into it and see all the relevant Kodi processes and the kodi.log shows errors relating to no display device connected.
If I manually turn on TV/receiver *first* then the Odroid initialises video and audio fine.
The problem seems to be that the Intel HDMI signal only tries to negotiate an EDID handshake *once*, early, during it's boot or resume process and if the receiver and/or TV isn't yet ready it doesn't retry and stalls video/audio over HDMI until sleep/resumed or rebooted once more.
So ... as Da Flex says - it seems to be a timing issue.
The quick and dirty workaround I have set up is to either
- add a 1 second delay to the Odroid's startup trigger in the Harmony remote software, to give the receiver time to bring up it's passthrough signalling and the TV to enable it's HDMI inputs fully.
- or start a different video source device group first (e.g. FireTV Stick or MS Remote Display Adapter which are also plugged into receiver HDMIs) then use the Harmony remote to switch to the Kodi/Odroid "activity" - i.e. Harmony knows that the receiver/TV are already on, so just switches receiver inputs and starts the Odroid.
I don't know enough about the low level video output process chain to say whether its an integral problem with the Intel chipset hardware, or if its something that could be addressed in software via the Linux Intel video drivers or LibreELEC tools/processes.