Please keep us updated on what you found worked for you.
I have basically had to go into the legacy view of 11.2 and completely remove everything I had placed into "that" system. I then went into 11.2 and re-setup the PLEX server, jails and THEN I also redid the entire permission structure (with recursive) and it finally worked. I have noticed, that every 3-4 days of "up-time" I have to restart my entire server, as it loses connection. This doesn't show in the FreeNAS GUI, as it still states up, but if I make it go down and then back up....BOOM...works again. I also have to log in to the FreeNAS GUI every day or I get this "token expired" message, which seems to lock out everything, including my drives I have allocated within Windows as my storage. Kind of irritating. I am assuming this will be fixed upon an actual release, instead of this very long BETA version that is currently out.
The plex user needs write permission to the folder where the metadata and covers get saved. That's it.
Try the following from inside the plex jail:
chmod -R 755 /usr/local/plexdata/Plex\ Media\ Server
chown -R plex:plex /usr/local/plexdata/Plex\ Media\ Server
I didn't want to setup a PLEX within a "jail;" rather, I want to use the plugin. If they rewrote the plugin to work with the new system with all of the "click to updates" and very user friendly access, that is the way I want to use it. I get that the PLEX server running IN a jail is the "preferred" method; however, I am confident that EVENTUALLY, they will get the plugin to work the way it is supposed to. That is the whole point of going to iocage and removal of warden with the complete re-writing of the code. They are spending time to make it work RIGHT, I will hope they eventually get it right and it should work. To me, that is like buying a new car, only to still use public transportation 100% of the time cause it "just works," every time. Doesn't make sense at all. But thank you!