More details: https://forums.plex.tv/t/plexamp-release-notes/221280/last
*Fixed*
- Don't show tracks from downloaded albums which aren't available.
- Make sure to complete incomplete playlists when startup refresh is enabled.
- Improve accounting for offline items and ensure it matches reality.
- Refreshing offline items could lead to missing content.
- Improve offline memory usage during refresh.
...and much more, please see link above.