A tip for anyone who changes their Nokia Media Transfer settings:
For example, if you are using Plus Music Fixer and you changed your phone's Nokia Media Transfer profile to not transcode your music, you may find some of your media stays in its converted form and doesn't get re-copied.
To fix this delete the files from your phone (use File Manager, or your computer), they are usually in Sound clips/External/iTunes Folder.
Then delete the converted versions from your computer. First quit Nokia Media Transfer from the menu bar and empty out Library/Caches/com.nokia.NokiaMediaTransfer/MediaFileCache.
Restart Nokia Media Transfer and re-transfer to your phone.