The only issues I am aware of with regards to the Update Service relate to the Local App Data Path and if the path originally in place is no longer there
Would need older logs as well (there would be 6 log files for each log)
and what is in the registry for
HKEY_CURRENT_USER\Software\Plex, Inc.\Plex Media Server\LocalAppDataPath
and
HKEY_USERS\.DEFAULT\Software\Plex, Inc.\Plex Media Server\LocalAppDataPath
