Dolby Vision Profile 8.1 with HDR10+ not working on LG webOS client

[Jollyrolly]

A mediainfo output or ffprobe might prove me wrong, but there doesn't appear to be HDR fallback metadata that I can see.

Media info is showing DV with HDR10 on all four files. Example from one that is not working:

Video
Title: 4K HEVC Dolby Vision Profile 8.1 (HDR10)
Codec: HEVC
Profile: Main 10
Level: 150
Resolution: 3840x2160
Aspect ratio: 16:9
Interlaced: No
Framerate: 23.976025
Bitrate: 14608 kbps
Bit depth: 10 bit
Video range: HDR
Video range type: DOVIWithHDR10
DV title: Dolby Vision Profile 8.1 (HDR10)
DV version major: 1
DV version minor: 0
DV profile: 8
DV level: 6
DV rpu preset flag: 1
DV el preset flag: 0
DV bl preset flag: 1
DV bl signal compatibility id: 1
Color space: bt2020nc
Color transfer: smpte2084
Color primaries: bt2020
Pixel format: yuv420p10le
Ref frames: 1
 

Do you have hardware acceleration or anything enabled? [...] and try to trigger a transcode

I don't have hw acceleration enabled. Triggering the transcode by limiting bandwith results in fallback to HDR on the file that is not working.

BUT:

you would want to manually remux those to MP4 with external subs if you want to keep DV. Otherwise, webOS client will always try to fall back to HDR.

Jellyfin 10.9.0 introduced "Support for Dolby Vision playback remuxing" and it's exactly doing that on all four files, no transcode or manual remuxneccessary anymore, Screenshot from within JF:
The media is in an incompatible file container (MKV, AVI, WMV, etc) but both the video stream and audio stream are compatible with the device. The media will be repackaged losslessly on the fly before being sent to the device.
That's the reason why I upgraded my JF instance in the first place. ;-) It's doing the remux on all 4 files, all are 8.1 DV with HDR10 - only that 2 of them aren't working as intended (DV Logo is showing but black/green screen) and I cannot make out what the difference to the working ones is