I'd hit up the Plex forums next. https://forums.plex.tv/
Since the last firmware update for my UN46F6300 TV the Plex application in the Smart Hub does not show shared content anymore. That area of the app is empty and it returns an error: "out of range or invalid:1" when it is clicked. This content shows and is accessible in my Plex Media Server and on my android tablet with a chromecast. I tried a Smart Hub reset and uninstalled then reinstalled Plex several times in the Smart Hub with no joy. Please advise. Thanks.