Are any items displayed if you apply the “Unmatched” filter to an affected library (after restoring it)? If so, that might indicate that some media became unmatched during your migration.
Speaking of that, can you describe the procedure you used to migrate your media? There should have been no need to restore from backup if you only migrated media (unless your database was corrupted). Provide as much detail as possible.
For reference, here’s the Plex-documented procedure for migrating media:
https://support.plex.tv/articles/201154537-move-media-content-to-a-new-location/
And here’s another method which is sometimes recommended here in the forums:
