iTunes 11.0.2 Update
Apple issued a new update to iTunes. Version 11.0.2 adds a new Composer view for music and improves responsiveness when syncing playlists with a large number of songs. The update also fixes issues where purchases may not show up in the iTunes library.
You can update to the latest version by going to iTunes > click the iTunes bar at the top left > click “check for updates” > click “update”.