If I log into the server and run the launcher command manually, it works fine.
Oct 10, 2018 17:26:29.326 [8040] DEBUG - “Plex Update Service Launcher.exe” “C:\Users\xxxxxxxx\AppData\Local\Plex Media Server\Updates\1.13.9.5439-7303bc002\packages\Plex-Media-Server-1.13.9.5439-7303bc002.exe” C:\Users\xxxxxxxx\AppData\Local “C:\Program Files (x86)\Plex\Plex Media Server\Plex Media Server.exe”