Loads of missing music from server

All of a sudden, loads of my music is missing from Plex. It’s still there on the share, and when I scan within Plex it’s not picked up any more. I noticed this because suddenly a bunch of my playlists are empty.

I can’t say exactly, but I’d estimate about 2/3 of my music is no longer being picked up. When I look in the directory, there are 1400+ artist folders, but in Plex it only shows 400 artists.

Can anyone offer any suggestions as to how I fix this?

Using server version 4.84.1

When Linux is involved, the first thing I check is file permissions:
https://support.plex.tv/articles/200288596-linux-permissions-guide/

If your media files are on an external drive, make sure this option is not enabled:

If the external drive doesn’t wake up in time for Plex to scan files, Plex may assume the files are gone, and will remove them from the Plex libraries if that option is enabled.

Thanks for the reply, it’s very useful. It is indeed a permissions issue. The Plex library is not really on an external driver per-say, it’s an Unraid setup, so Plex is running on a container on the server along with the shares.

Sadly that option you mention was checked, so I don’t think I can recover play counts and other lost data.