That must be what is missing from the add-on as that is what this thread I just voted for is about “Plex integration should have an update sensor”. Hopefully and updated to the add-on will come out if enough people vote for the feature. My guess would be not a lot of people are using PMS inside HA. 
Feature Requests
2 votes
Nope. Plex Integration, is the thing you add to Devices and Services - it lets you monitor the libraries of a plex server, tells you when someone is watching something, and gives you media_players for the various players that the plex server reports are connected to it.
The add-on is the ability to run the Plex server on HAOS. The add-on is what has the update sensor.
Could the fact that I have 2 PMS running on my home network be causing an issue? I have one on my ShieldTV and the new one on my HAos
No - it looks like the problem is that the address Plex is trying to access behind the scenes is the servers Docker IP address and NOT it’s LAN address. In the Plex server settings (not the add-on, the actual plex server) - go to network and part way down that page (which may or may not be hidden behind the “advanced” button. There is a dropdown for the network interface. Check there.
I see that entity in my Plex Media Server integration, but it just reports “unknown” all the time. My Plex itself is hosted on a separate Ubuntu server.
I checked and noticed that it would incorrectly mark the sensor as Unknown if the version was current. I put in Properly mark Plex update sensor when current by jjlawren · Pull Request #113197 · home-assistant/core · GitHub to fix this.
Hello again everyone! I am back with some more questions. So I read through the plexupdate info and even what is posted on wiki. It all talks about Linux and Linux commands but since HA is based on Linux I take it that it works the same way?
I ran the “git” in terminal and it seems to have installed without errors as shown in the first attachment but after that point I am a bit lost… it talks about setting up a
Cronjob in /etc/cron.daily/ directory but in HA I can only find /etc/crontabs/root as shown in the second attachment. So that is about as far as I got with setting up the automatic plexupdate to make life simple, am I getting close? 
