I was running the beta of plex that allowed for server metadata to be stored on the internal user (sdcard also in my case) on shield experience 6.3 and all was working and happy.
The preview update for shield experience 7 came which I installed along with any and all updates including plex and it’s server. It totally borked my shield server and rendered it basically permanently off line. No matter what I did such as reboots, remove and reinstall the plex apps, try to put server back on internal. Nothing would bring back the shield plex server. Seems the update rendered the sdcard disconnected somehow, which for me, not even reformatting it would bring the plex server back on line. What a mess!
I ended up having to do a total factory reset of the shield and start fresh which worked. Even migrating the meta data to the Sdcard after I reformatted it and set it up correctly worked. Kind of a pain, but it’s all happy again. I was able to apply shield 7.0.1 and again server was off line. A simple reboot brought that back. The absolute latest and most recent update applied perfectly.
Not sure I’ve helped you, but for me, all I could come up with and doing much reading on the GeForce forums, was a factory reset.
Hopefully someone else will have a better solution.