Android BM App Galaxy S23+ Only Green in HLG10

Hey all,
Has anyone had the BM Camera App not work on a Samsung Galaxy S23+ in BT2020 HLG10 mode? I only get offered Rec709 or that mode so wanted to go the HLG10 for (what I assume is) greater bit depth.
Holding the phone portrait the camera viewfinder just got solid green. Audio bars moving and you can record but just a solid green screen. Turn phone landscape and now the viewfinder shows what the camera sees. Great. Record works. However, once done all I get is a media file that's solid purple colour. Tried bringing it into DaVinci, no luck. Just a solid colour.
Works find in Rec709, but as soon as switching to BT2020 the whole thing fails to record anything usable.
Do I need to install some sort of codec or anything fancy to make it work in this mode or is the S23+ already too old?
Has anyone had the BM Camera App not work on a Samsung Galaxy S23+ in BT2020 HLG10 mode? I only get offered Rec709 or that mode so wanted to go the HLG10 for (what I assume is) greater bit depth.
Holding the phone portrait the camera viewfinder just got solid green. Audio bars moving and you can record but just a solid green screen. Turn phone landscape and now the viewfinder shows what the camera sees. Great. Record works. However, once done all I get is a media file that's solid purple colour. Tried bringing it into DaVinci, no luck. Just a solid colour.
Works find in Rec709, but as soon as switching to BT2020 the whole thing fails to record anything usable.
Do I need to install some sort of codec or anything fancy to make it work in this mode or is the S23+ already too old?