- If there is a _lot_ of media, it will take a few hours before it is all scanned into the database
- Have all your mp3 files got id3 metadata tags? If not, you will only see them when you choose the Filename sort mode in the UI (ie not the Title, Performer, etc sort modes, after all it has no information upon which to provide that sorting without the meta data)
- Note that any network shares (or external drives) that you add, and it discovers, it will ask you whether you want to use the LinuxMCE folder structure - ideally, you should say Yes to this, it will create a similar folder structure on the drive, then you move your media into the appropriate folders on that external drive/share... without using that option, un-tagged media will be invisible even in Filename sort mode
- As mentioned, use the web admin to determine whether the files are visible and in the database... absent means they are not even visible, black text with a drive icon means they are visible but not scanned into the database for some reason, green text with a big tick icon means they are visible and in the database. There is also a tick box option to show files that are in the database but not online, if they are there then it would suggest that the system doesn't see your drive as online for some reason.