I have recently installed Plex on my Asustor NAS and successfully added content to a library of which I can view across my devices.
However, when I added content to that library, I cannot see this, even though the previously added files and the newly added files are in the same place.
Is there something that I should do when adding content to an existing library?
You can configure your server to automatically or periodically scan your library (Settings > [Server Name] > Library). Automatic scanning isn’t supported on all platforms (external or network shares usually don’t trigger that kind of events on the OS to notify Plex)