Synology DSM 7.2.2 upgrade - Plex no longer working

To get PMS to reconnect to your account you need to reclaim it.

Below is the FAQ on how to do this ( with screenshots )

If you’ve upgraded from DSM 6, you will have to perform other steps.

Please advise if this was an upgrade from DSM 6 → DSM 7.2.2
or an upgrade from regular DSM 7 → DSM 7.2.2