The September 2018 fixed an issue with memory use within the Plex Media Server transcoder. There is still a memory issue when hardware transcoding and this is being looked into by the nVidia Shield team. I would not mind getting more recent logs and sample files that bring on the problem - ideally a file no more than 1Gb in size - using tools such as mkvtoolnix to extract the first 500Mb or more of the file. It needs to be long enough to actually bring the problem on when hardware transcoding and logs from the server and the client app.
https://support.plex.tv/articles/201643703-reporting-issues-with-plex-media-server/
https://support.plex.tv/articles/200250417-plex-media-server-log-files/
https://support.plex.tv/articles/201035968-generating-sample-files-from-media/
https://support.plex.tv/articles/201573117-android-android-tv-fire-tv-logs/
