I never said it did... I was just pointing out that it was clear how to update Plex if you just read the page. However, putting an environment variable as an extra argument, is absolutely not right.
Then we'll have to agree to disagree about that point.
I had "-e VERSION=docker" and it did not update Plex after a number of machine restarts or container/image restarts. My Plex web interface still said an update was available. That's when I started digging for more info.
I don't remember now where I found the information to use that string "-e VERSION=latest" as an extra argument, but.... it worked.
Once I changed that to "-e VERSION=latest", on the next machine restart (or container restart, I forget which) it updated Plex.
I'm using OMV 4.x and the relevant Docker, not the Plex plugin in OMV extras, if that matters.