It appears nobody likes to support Plex, not even Plex community support on the Plex dot TV forum as nobody tried to answer these simple questions.
The answer is that is that if you are unable to disable Plex and delete the Plex folder and restart, re-enable and connect, then you may have to do a factory reset (back up your data before you do this).
Plex is ultimately a third party product. Western Digital doesn’t develop or update it except by making it available. WD is pretty clear about supporting third party products in that the support is quite limited.
So you are mostly on your own with trial and error when trying to make Plex work on the MCH.
