Thanks for your explanation.
So basically all x86 hardware doesn't support HDR until LE10.2 or probably L11/K20. So it's either use the Windows version or these community builds or Rpi4
Certain allwinner, amlogic, and rockchip devices also support HDR but YMMV with those platforms.
Fix your network?
Otherwise usually the best option is to map a single key or remote button to do it, Keymap - Official Kodi Wiki
Well LE10 could have ditched x86 if they just said sorry no to nvidia users.
You still wouldn't gain HDR 
Just use the "Wait For Network" option in Kodi and in the LibreELEC settings add-on
Why won't it make it to the LE10 builds? I'm happy to test but in the end I prefer to go back to the original releases and follow their update cycle instead of relying on SMP. Would be a shame to consider replacing this NUC (7i5) if if it has the ability to work but not with the official build.
It's less about LibreELEC and more about Kodi. Kodi 19 is already in a release cycle so that means no new features and only bug fixes. So that means now that the Kodi 20 development window is open it is possible to get it merged in. I don't spend a lot of time on this though as it's very consuming and requires a lot of work.
So Kodi 20 is aimed for LibreELEC 11 which may gain x86 HDR support if I merge my work. If people want to take these patches and create their own builds that's possible also. They can also backport the patches to LE10 if they self build.
You can either use the whitelist and enable the double refresh rate option or you can keep the whitelist empty and it will switch to the 50hz mode automatically.
Both options require you to have "Adjust display refresh rate" enabled
Seems odd that you got stuck on that mode. You should reset your video scaling method by using the "Set as default for all videos" option in the video OSD after selecting a valid scaling method.
smp do you know if the patches you used in post 502 will be included in LE10?
Or would you need to keep building new releases with those patches?
They won't be in LE10
The latest beta
you can upgrade, just be prepared with a backup
Are you actually using a displayport connector or is that symptom of LSPCON? If so can you try an HDMI port?
add debugging to the cmdline.txt file and the LE settings debug info will show up in the kodi debug log
Then what can I do to fix it, I also saw some other created thread in libreelec forum that have the exact same problem I think but I am not sure. But anyway what do you think i must do in order to resolve the issue
Thank you for your help in advance
Nothing really. Consider the RPi4 build still a work in progress
No idea how this works and I would consider it "not supported"
Looks like you need to use the following in config.txt (no idea if it's valid though)
dtparam=i2c_arm=on
dtoverlay=hifiberry-digi