From the beginning, but I’ve tried again just now and it works fine, should be something failing in the chain, because I turn off and on again the reciever (Denon X3100W) and it works now, the strange thing is yesterday was failing only for that movie and not for others, so I shouldn’t discard is also a problem of Plex.
Absolutely, I was the first one that used the example of the little girl cheeks on Doctor Sleep movie, but it’s not only a problem with DV movies in Plex, it also happens in Netflix. It’s relatively subtle but it’s clearly there, and frankly, you spend a lof ot money on a OLED TV with Dolby Vision + Shield and you expect perfect reproduction of colors, and that is not a perfect reproduction in my opinion. 
Looks like they can’t catch the problem they said they are doing all correctly and they wrote Dolby to ask but didn’t get an aswer.
PQ = Perceptual Quantizer
From the Wikis…
The perceptual quantizer (PQ) , published by [SMPTE] as SMPTE ST 2084 , is a transfer function that allows for the display of high dynamic range (HDR) video with a luminance level of up to 10,000 cd/m2 and can be used with the Rec. 2020 color space. PQ is a non-linear (EOTF). On April 18, 2016, the announced industry guidelines for UHD Phase A, which uses (HLG) and PQ transfer functions with a bit depth of 10-bits and the Rec. 2020 color space. On July 6, 2016, the ITU announced Rec. 2100, which uses HLG or PQ as transfer functions with a Rec. 2020 color space.
Dolby Vision is an HDR format from Dolby Laboratories that can be optionally supported by Ultra HD Blu-ray discs and strea,ming video services. Dolby Vision is a proprietary format and Dolby SVP of Business Giles Baker has stated that the royalty cost for Dolby Vision is less than $3 per TV. Dolby Vision includes the Perceptual Quantizer (SMPTE ST 2084) electro-optical transfer function, up to 8K resolution, and a wide-gamut color space (ITU-R Rec. BT.2020 in YCBCR or ICTCP.
So Dolby Vision is the dynamic metadata that sits on top of the PQ HDR. If a device can’t reproduce the Dolby Vision Metadata, the device drops back to PQ HDR.
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It drops back to the PQ EOTF.
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HDR is the generic name for all the formats.
The ‘basic’, royalty-free format is HDR10. HDR10+ is Samsung’s enhanced version and, obviously, DV is Dolby’s to whom the studios must pay royalties.
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Not just the studios, but also the TV manufacturers. HDR10+ is supported by Samsung, Panasonic and Vizio, to name a few. HDR10+ is also royalty-free, as Samsung doesn’t seem to like paying royalties as I’ve never seen a Samsung device that supported Dolby Vision. 
Most players have that option. On my TV and Nvidia Shield I can choose a resolution that does not support DV playback and watch HDR10 only.
Plex already recognises if you have 2 versions of the same film (say UHD and HD) and lets you choose so implementing a choice of HDR10 or DV doesn’t seem like it would be that hard.
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Update to say that something was wrong with Shield because the issue also happened to me using Netflix. So it is not probably a problem with Plex, unless they need to restore or clean something after stop playback and they didn’t (pure especulation, but it’s true it nevers happened to me until now I’m playing testing those new MKVs with Plex).
DV is working for me, but for some titles you have to stop and start them again sometimes more than once before DV triggers. The title I have had the most issue with is The Matrix. For some reason that one is very stubborn. I assume this is just going to get more stable as Plex pushes more updates. Using a shield tv here.
I’m having real problems with Days of Thunder. It won’t even play unless I select the vanilla DD soundtrack and then it will only work with HDR.
If the TruHD track is selected - nothing!
Same here:
Sometimes it works, sometimes it transcodes, sometimes it works but gives off red / blue / green tints, and sometimes it just doesn’t work, and at that point, restarting the Shield (2019 Pro) is the only fix.
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I’ve never had it transcode, the most it does is just default to HDR10. I did see the red tint thing on The Matrix one time.
Yes, in my case, when it defaults to HDR10, it’s transcoding. At the same time I lose lossless audio (Atmos / DTS:X).
It gets worse when I switch from a DV file to an HDR one, then back to a DV file, more often the problems show up – tints, transcoding, etc.
Have you tried checking playback info when it defaults to HDR10? Mine says Copy for video and Transcode for audio. But when it plays DV, audio plays just fine.
Also for some reason today, most of the time it plays DV, unlike yesterday – it’s like 50/50.
Check your dashboard when it plays in HDR, if it’s a TrueHD title it will be transcoding the audio to EAC3. DTS titles just tend to be direct streamed instead of direct played when falling back to HDR.
I will check this out. I wasn’t looking at the dashboard at all when I was doing this. Clear some kinks are being worked out but we’re on the right track at least!
NVShield Pro Player app updated to 8.8.0.21167 (c37f7b87)
Server 1.20.3.3437 (Win 10 Pro)
I am reporting the same behavior as before. Some titles play immediately in DV/ATMOS, a few will randomly fallback to HDR10/Transcoded audio (Spider-Man: Homecoming, The Matrix, The Crimes Of Grindelwald and Top Gun). Starting and stopping will push into DV/ATMOS after two or three attempts.
As a control, I ran Star Trek (2009), Dark Phoenix and A League Of Their Own. All three are HDR10 only with ATMOS audio. These three played with HDR10 and the correct audio track with NO transcoding.
Having DV metadata on the video track is still causing a fallback to HDR10/Audio Transcoding, but in the absence of DV metadata, HDR10 is handled with no issues.
Assuming the update was NOT related to the DV/HDR10 issue
Nope, it clearly says:
- [TV] Preplays: app would crash when navigating to a list of tracks from a movie/tv show.
- [TV] Player: clicking “More” in audio player cause app to crash.
- [TV] Preplays: “Add to my X” button couldn’t be focused on older devices.
- [TV] Photos: app could crash when closing video playback in a photo library.
sixones has already explained what is happening when Plex plays HDR instead of Dolby Vision.
This is trickier than it sounds, as the Android OS doesn’t give us any indication of which display mode supports Dolby Vision or HDR10+.
To give an update on this, it appears to be an issue with the Dolby Vision decoder it appears to randomly crash when we configure it, this causes us to fallback to transcoding. Currently the only workaround for this is to back out and replay until Dolby Vision plays and the decoder doesn’t crash.
This appears to only happen with certain profiles and videos, whilst others will always playback successfully.
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