I don't use Plex often, but decided to check it today using my Ultra. I used both the "official" Plex channel, as well as RARflix. I enabled forced direct play, and did not select captions, as that would override the direct play and force transcoding to extract the captions. I found my DTS-MA files played the DTS core correctly, with no observable sync issues. Of course, I didn't play each selection for very long, as I don't have time right now to sit and watch a full movie.
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When using RMP and my DLNA server, I also get the DTS core without issue. I have trouble with playback on the first 6 Star Wars movies, but that is due to something they've encoded in the video, not the Roku player. I have the same issues using my Sony BD player for DLNA playback.
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I am connected through a Yamaha AVR to extract the audio. Sure wish we had HD audio bitstreaming... 

How funny... i was just noticing the same thing with the first 6 star wars movies... it may be due to the 6.1 surround sound audio? I'm not sure what else it could be. 
The only way it works with audio is if the entire video/audio stream is transcoded... you seeing the same thing?

tomiy1 wrote:

How funny... i was just noticing the same thing with the first 6 star wars movies... it may be due to the 6.1 surround sound audio? I'm not sure what else it could be. 
The only way it works with audio is if the entire video/audio stream is transcoded... you seeing the same thing?

Well, it's 7.1 audio, but you could be correct about that. From what I understand, Plex has several transcoding profiles for the Roku players, and they may not be optimized for the latest, more powerful players. I use Serviio for most of my streaming, and he only had a single profile for Roku. I developed a bunch of new ones that work better for the later players, and they will be published with the next update (possibility this weekend). While Plex has a very nice user interface, I much prefer using a DLNA server that I can tweak if desired. Modifying Plex profiles is very difficult. 

Can we get a response from a Roku Employee about this?  

Have you guys tried changing the HDMI and S/PDIF settings from 'Auto' to 'Dolby Digital, DTS'. That fixed it for me. Auto detect and Dolby D+, DTS both introduce lip-sync issues with my set-up.

lower to lossy audio to fix sync issue? (sigh)

holygeesus wrote:

Have you guys tried changing the HDMI and S/PDIF settings from 'Auto' to 'Dolby Digital, DTS'. That fixed it for me. Auto detect and Dolby D+, DTS both introduce lip-sync issues with my set-up.

I have tried it both ways. Setting to auto results in just stereo for me. Setting to Dolby Digital, DTS results in the severe delay with DTS audio tracks. I always set mine to "Dolby Digital, DTS" instead of Auto Detect anyways. Right now I have it set to just Dolby Digital so that Plex will transcode DTS to DD to avoid the issue.

cocokola wrote:

lower to lossy audio to fix sync issue? (sigh)

It's all lossy audio 
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DD+ isn't any higher audio quality. It's as good as standard DD with a lower bitrate. 

Registered to voice my displeasure with this bug. Has been an issue for months using the Emby app. A fix is long overdue. 

I too am chiming in with my frustration with regards to this bug.  This has been an issue since I first bought my Roku Premiere+ and I am currently on the latest build 7.7.0.4139.  I do hope that this is something that is still being looked into.

I just picked up the Ultra, and use PLEX almost exclusively.  A few days ago I had purchased the premier and noticed this syncing error and I was bummed out.  However when I got up today to trouble shoot it some more I received a new update (I can't remember the version number, I am away from my house at the moment) and DD and DTS worked just fine.  I went and upgraded to the Ultra as my setup needed the Optical out.  Again, did the latest update. HDMI is set to DD and DTS (per my receiver specs).  Audio is set to Auto (DD and DTS).   Works perfectly.  Ran Guardian of the Galaxy with DD and The Force Awakens in DTS, I also ran a few things off of Netflix and didn't see any issues all day.

Justed tested my Roku Ultra with a bunch of DTS audio movies and unfortunately all still exhibited the audio sync issue. My Roku was up-to-date at the time of this writing with v7.7.0 Build 4154-29.

I’m not sure what the previous poster did or what version he has, but it definitely still does not work and has major lag.

DTS absolutely does NOT work on my Roku TV when output through HDMI ARC or optical. no change in the latest 4154 update that came out a couple days ago.

Plex, Emby, USB stick - all are out of sync by at least 300-400 ms with DTS, and it gets worse with any pausing/restarting. actually [font=-apple-system, Helvetica Neue, Helvetica, sans-serif]all audio has a slight delay through hdmi arc and optical, though not nearly as severe as with DTS. [font=-apple-system, Helvetica Neue, Helvetica, sans-serif]can't even fix it with AV receiver sync setting since that only delays the audio even further.[/font][/font]

I've given up expecting a fix at this point, it's going to be a full year pretty soon. 

Interestingly plugging my Roku Ultra directly into the AV receiver has no issues with DTS. of course the whole idea of a Roku TV is that we wouldn't have to plug in a separate roku...

holygeesus wrote:

Have you guys tried changing the HDMI and S/PDIF settings from 'Auto' to 'Dolby Digital, DTS'. That fixed it for me. Auto detect and Dolby D+, DTS both introduce lip-sync issues with my set-up.

Amazing, it fixed my lip sync problem!
Thanks for your suggestion!

Still have the DTS audio sync bug with Roku OS 8.0.0 4108-29. I got a new receiver recently too, so I knows it’s definitely not a receiver issue; definitely the Roku Ultra!