I’m at my wits end here, spent countless hours trying different things.
System details:
Ugoos AM6B+ (S922X-J I guess)
TV: Sony Bravia KD - 50X85K (DV fully supported, no FEL)
HDMI input in the TV settings have DV support enabled.
4 different HDMI cables tried, including the one from PS5 (works correctly on PS5 with all bells and whistles), and a really fat one with 8k support.
CE-ng Builds: 21.2 stable, 21.2 nightly 20250519 (generic).
I’ve followed guide steps to the letter - correct dtb and dovi.ko in the rootdir, recovery boot, setup, ceemmc -x.
System info/Video shows DV in the supported list.
Settings/System/CoreELEC shows DV-related options.
The problem: both when running from the flash drive and from emmc, most of the times* the DV videos look like this:
The example above is TV-Led. If I select Player-Led, it’s even worse (can’t attach a second image, but basically it’s all greenish on the top half of the screen, and completely black on the bottom (not even player controls visible).
The TV does not report it as DV content, too (not even HDR).
Non-DV HDR content plays fine.
After playing several different videos like this, journalctl -l | grep -i dovi output looks like this:
dovi logs
CoreELEC:~ # journalctl -l | grep -i dovi
May 20 23:45:14 CoreELEC dovi-loader[3583]: run dovi ‘start’ for ng
May 20 23:45:14 CoreELEC dovi-loader[3583]: loading ‘/flash/dovi.ko’ module
May 20 23:45:14 CoreELEC kernel: dovi: disagrees about version of symbol module_layout
May 20 23:45:14 CoreELEC kernel: dovi: module license ‘AML’ taints kernel.
May 20 23:45:14 CoreELEC kernel: dovi: disagrees about version of symbol register_dv_functions
May 20 23:45:14 CoreELEC dovi-loader[3654]: filename: /flash/dovi.ko
May 20 23:45:14 CoreELEC dovi-loader[3654]: license: AML
May 20 23:45:14 CoreELEC dovi-loader[3654]: description: Amlogic Dolby Vision Driver
May 20 23:45:14 CoreELEC dovi-loader[3654]: depends:
May 20 23:45:14 CoreELEC dovi-loader[3654]: vermagic: 4.9.y SMP preempt mod_unload modversions aarch64
May 20 23:49:37 CoreELEC kernel: DV:[0,0,12,DOVI,352,0]
May 20 23:50:06 CoreELEC kernel: DV:[0,250,12,DOVI,504,0]
May 20 23:50:31 CoreELEC kernel: DV:[0,431,12,DOVI,352,0]
May 20 23:51:06 CoreELEC kernel: DV:[0,548,12,DOVI,368,0]
May 20 23:51:49 CoreELEC kernel: DV:[0,694,12,DOVI,368,0]
May 20 23:52:03 CoreELEC kernel: DV:[0,808,12,DOVI,456,0]
Weirdly enough, immediately after booting a fresh install from the flash drive, playback almost works fine - most of DV videos play normally, TV reports it as DV, the only issue I saw was some blinking in a test file with P7 FEL.
I’ve noticed that after rebooting CE, usually the playback breaks like in the images above, and never goes to normal again.
I feel really stupid to go and ask questions on the forum here, sorry for taking your time, but I’ve exhausted all other options by now. Googling, searching for answers in forum discussions here, asking chatgpt - nothing helped 
Please save me, I would tremendously appreciate any help on this issue, and have a wonderful day 
edit: I should add that other media players, and the am6b+ box itself (in the android mode), output DV content correctly to this TV, no image distortions and in the DV mode.