EDIT: This issue has been fixed.
To give a better idea of the black OSD issue, here are two photos (sorry for the quality) and a screenshot. This problem is only present during DV playback, and not SDR, HDR HDR10+, HLG content.
Black subtitles (not nearly as easy to see in darker scenes)
Black player controls
The correctly colored OSD is present in the screenshot (kodi-send --action=“TakeScreenshot”)
It’s as though there is a black mask over the OSD.
At @Sunset1982 I tried a few of the CM2.9 & CM4.0 samples from the link @Kaan provided. I struggled to see any difference between CM2.9 and CM4.0. Or in the CM4.0 demos when different components were being removed. If the am6/u22xj doesn’t support CM4.0, then I doubt the Cube does either. If they do support CM4.0, I would need to take another look. I’m not sure how subtle the effect is, I struggled to see a difference even in the YouTube comparison I checked out.