That is actually a display bug that I didn’t notice before, which means I may have been responsible for introducing it … Note that this is only a display issue and that the ENV variables are actually passed onto the docker run command. I just tried to install the Plex rock-on on my dev machine the install went fine and I can access the Plex UI. As you can see below the ENV variables are passed correctly:
Let’s try to see what is happening there, the install of some rock-ons can take a little while sometimes and cause this kind of oddity in the UI. Sometimes I’ve seen a simple page reload (Ctrl + R or Ctrl + Shift + R on chromium-based browsers) or clicking the Update button fix this but that is an aspect we still need to improve.
From your message, I understand you did not encounter a proper error message, so I would expect the rock-on install did proceed correctly, although I seem to see in your earlier screenshot an error message stating that the previous Plex install failed. Could you clarify this?
If the former is true, then you could verify that the underlying docker container is indeed running as expected by running docker ps -a.
If the latter is true, I would recommend you to look into the logs listed in the error message (rockstor.log) for a relevant error message around the time of the install attempt.
Hopefully we’ll have a better idea of what the problem is.