Let me jump in here and correct some misinformation posted.
If you want your OSD to remain in HDR mode (either HDR10 or Dolby Vision), you can make the following settings changes:
- Change the Video Output Behaviour to "Avoid video mode changes"
- Under Advanced Options, change High Dynamic Range Format to either "Prefer HDR10" or "Prefer Dolby Vision Standard" as is your want.
If you make those two settings changes, your OSD will remain in either HDR10 or Dolby Vision mode per your selection for item 2. Note, however that your video output when playing movies will
also be in that mode so either always HDR10 or always Dolby Vision.
There is no setting change you can make that will have the OSD in an HDR mode but still allow movies to play in their native HDR colour spaces..