Exporting Playlist Problem!!!

I've been using Rekordbox for quite a while now and never had this problem until yesterday!!

When I export a playlist onto my SD card, I'm getting duplicates of some of the tracks and some of the tracks are missing.

If I try and export the missing track into the playlist on the SD card, It claims that the track is already there but I cant see it!!!

I've formatted the SD card and it's still happening.

Any advice would be really appreciated.