Most of my DVD sourced files retained the anamorphic aspect ratio with using DAR for correct playback.
That has never been an issue with Plex, but the new experience app plays those files back with the wrong aspect ratio.
However it seems it may even apply the DAR, but in the wrong direction (making the picture even more narrow then wider).
Screenshots for comparison.
Forcing a transcode is fixing the issue (because aspect ratio problem is caused by the new app).
In the new app, during playback tap the vertical ellipsis in the bottom-right as shown in your first screenshot. From there, tap Playback Options -> Display Mode. You should have 4 options: Original, Letterbox, Stretch, and Zoom. Try either Letterbox or Stretch (I believe it defaults to Letterbox already, so try Stretch).
This setting is persistent. So if you play something else back and it looks oddly stretched, you’ll have to change the display mode again.
These settings have nothing to do with the problem.
Stretch will stretch the image of course, but will not respect the correct aspect ratio in any way.
This wasn’t a suggestion to fix the underlying issue. It was intended as a troubleshooting step to further characterize the issue. What I’d hoped was that they’d respond and share their experience so that the issue could be better understood. I’m sorry I didn’t make that clear.
The issue is clear. New Plex player doesn’t respect DAR value, but plays aspect ratio always as 1:1 instead.
Ah, sorry. When you first replied I didn’t realize you were the OP. My mistake. Would you prefer I remove my posts so as to not clutter your report?
No problem, everything is alright. Thanks for trying to help. 
is this a bug with the new version of the app? how do we fix it permanently? are the dev team aware?
Are you able to provide a sample? I can take a look, it should be the same as the old app on Android it’s the same stack but we now direct play a lot more content.
Not at home this weekend, can provide a sample next week.
Media direct plays in both app versions.
I can’t provide a sample (because it’s from my live tv) but if I play it back to back on the Nvidia Shield (legacy client) it displays fine and then on my Android phone (new client) it displays squished.
I can provide a video sample but I can’t promise that it’ll be very good 
I’ll upload it to imgur now and update this post with a link when I can.
Update:
Sorry, I meant if you could send me the video that you were playing (or just a sample of it). You can either share it to me via Plex web (same username), or upload the video to somewhere like Google Drive.
Oh of course, give me about an hour or so, sorry!
I found the same issue when I received the new android app this week.
Thanks for the sample, I’ve been able to reproduce the problem and found a solution.
You can sideload the APK below to try it out, it should be available in the next release (via Google Play in about 2 weeks).
Thank you for posting this and providing a sample, I only noticed this issue last night and was about to do the same! Thanks as well to sixones for the quick fix and keeping us all informed!
The fix here is for Android. I see the same problem on the iOS app on an iPad. Is there a fix coming there as well?
Hiya! Would you mind giving us a bit more information? What version are you running on the app? And what exact issue are you experiencing? If there are screenshots, a video, or other information that can help us identify the issue that would be much appreciated.
