HLG -> HDR (ST2084) = odd colour shifts & artefacts

My full project settings are outlined in this post - but basically,

if I simply drag a 10-Bit, 4:2:2 AVC UHD 50fps HLG Clip into resolve and set the Project Settings to:
- ACES Input: Rec.2020 HLG (1000 nits)
- ACES Output: Rec.2020 ST2084 (1000 nits)

Then render using:
- H265/NVIDIA/Main 10
- Embed HDR10 Metadata

I end up with an HDR output that has odd colour shifts and artefacts in some of the background whites (see the white window pane behind the colour checker).

I've gone round the bend playing with the "Color Space & Transform" in the Project Settings and the Render Settings but anytime there is a combination where the Input and Output options are different in the Project Settings I see this issue (both ACES and Davinci Color Managed).

HLGtoHDR.jpg (1010.11 KiB) Viewed 1569 times

...and here is an example of just using "DaVinci YRGB" / "Rec.2100 ST2084" in the project settings. The white window sill looks better (but everything now looks oversaturated to my eyes).

HLGtoHDR_no_color_mgt.jpg (979.3 KiB) Viewed 1568 times

Try this, changing only the Frame Rate and Key Frame as needed.

Report back.

HDR Export.png (43.98 KiB) Viewed 1567 times

Thanks Jim,
Still have the same issue, I've also included my render settings in the image.

HLGtoHDR_RenderSettings2.jpg (518.51 KiB) Viewed 1550 times

You changed the Quality from my posted image. Also the Lookahead. Don't do that.

Also, Key Frame should be half the frame rate. 25 in your case.

Try again, report back.

Next try - Still no change:

HLGtoHDR_RenderSettings3.jpg (477.25 KiB) Viewed 1546 times

FYI - It seems to be a chroma sampling issue, as if I change The Encoding Profile from "Main 10" to "Main 4:4:4 10" the issue goes away (but 4:4:4 is no good for real time playback).

If it helps - here is a link to the source file (17sec, 1gb) - https://behome.dyndns.info/index.php/s/zfLpWjBpSFCLsN7

OK - Looks like there are a few things make this chroma issue less visible.
- Shooting: This clip has plenty of noise (I shot the same scene again in better light with a lower ISO and it was much better, but it still existed on some parts of the window frame).
- Playback: Using DXVA2-Native HW Acceleration for Video Decoding on Windows increases Chroma Blur especially on NVIDIA cards. Using DXVA2-Copyback, D3D11, CUVID or even turning HW Acceleration OFF works pretty well but comes at a performance cost. Changing this had the biggest impact on hiding the issue.

I also updated my Project Profiles (as attached) as the FX6's HLG mode is actually Rec.2020 / ARIB STD-B67 HLG and that helped the final image look better..... though I'm unsure if the settings are correct, esp after the Output color space.

NewSettings_Project.jpg (134.07 KiB) Viewed 1528 times