Sony Bravia 4K TV - Plex stutters on DVD rips from Synology NAS, DS Video doesn't

Hi, I’ve got a Sony Bravia XE93 TV running the latest Plex client for Android TV, and I’m having a problem with stuttering video when viewing DVD rips in Plex, that are stored on a Synology NAS running Plex server. The odd thing is that on the same TV I can use Synology’s own DS Video app to view the same file without stuttering, and also on a Nvidia Shield TV connected to the same TV, running Plex on that against the NAS.

The stuttering is about once every 5 seconds, and is very noticeable during panning shots or even moderate movement on screen. I’ve checked that the video is set to show the original so I don’t think any transcoding is going on, just that the Plex client on the TV itself is stuttering.

Any ideas on what I can do to troubleshoot?

Thanks
Andrew

Just found the posts that say downgrade to 6.12 - done that and it works again.

Hi I have a Sony 900F with the flickering line at the bottom of letterbox movies , since upgrading to the latest play for Sony player 7.0 or something , how do I down grade ? Thanks