Been looking all my DV movies really close to the TV, because sometimes the black bars are darker as hell, but still there... And they're in all movies, in a moment or anotherLooking at disks, some have the unstable black issue, others do not. So authoring must matter.
I have not seen the black issue on the native LG Netflix app.
It may have something to do with transmission over HDMI. That is in common to disk and ATV4K playback.
The issue does not get much press but it may be the reason for delayed support on disk players and displays.
The ATV4K went all-in on DV and there are clearly Netflix playback problems with the LG (and perhaps other displays).
That should raise the stakes.
Anyway, update from John Archer from Forbes, as he told me right now:
So as i said, or it is a DV Firmware problem, so all TV's with DV Chipset will need to be updated, or it is a DV API problem that could be solved with newer DV API for all players/TV, which could explain the delay of DV UHD players...LG have told me their own investigations show it is not their fault. Have a meeting with Dolby tomorrow.