[gil80]

Yes, running the latest. The auto colour switching doesn't work, according to the TV HDMI service info menu when the Shield is set to Rec2020 DV and HDR10 Ready, regardless if auto-switching is enabled. It will only auto-switch between the profiles if Rec709 DV and HDR10 Ready is selected.
This is off-topic, of course, but interesting find. If you have an LG TV, I can explain how to test that.

p.s. - kodi 18.9 is using a lower version for the backup addon than kodi 19.0. I cannot restore due to some error which I have no idea about.

If you are talking abour the '111111' hidden menue, the menue is buggy and does not always display the correct color space information, especially for DV. The shield is tunneling DV in an 8Bit RGB tunnel and this is confusing for the menue and can cause bugs to display wrong information.

Yes, that hidden menu.
The fact that the HDMI report shows SDR content for DV is a known bug, but there's another menu that can tell you if the colour space is BT2020 or not.
In the LG remote, there's a ... button. Clicking on it and selecting TV> Information will display at the bottom the resolution, the color space, and if it's PCM or not.
If the Shield is set to auto switch colour spaces and the Custom Display Mode is set to Rec709 Dolby Vision and HDR10 Ready when playing DV or SDR, it is not coming up as BT2020. When playing HDR it comes up as BT2020. The switching works.
If the Shield is set to auto switch colour spaces and the Custom Display Mode is set to Rec2020 Dolby Vision and HDR10 Ready when playing DV, SDR or HDR it always comes up as BT2020. The switching doesn't work.

As for the backup addon, I couldn't find a compiled version in the repo that is greater than 1.3.x for Kodi 18.9. I'll do some more digging and experiments. thanks for the info.

Further testing of DV with your Kodi build, one thing that I was happy to see that is working is the BluRay rip of Spears & Munsil 2019 UHD HDR benchmark. It was able to display HDR and DV whereas this rip didn't work at all on Kodi 18.9. However, when selecting DV benchmark, it shows that my monitor is not compatible to display DV MEL and FEL and not compatible to play HDR. I wonder why it thinks so.