The file is already in the location error

Hi, I've seen a couple of other posts in the forum with the same issue, however I believe mine is unique in the sense that I've not moved any music around, at all. Tracks have just started disappearing from their location. 

I have followed all videos and support to relocate tracks (by watching this Pulse video https://www.youtube.com/watch?v=7o6ro9cXqbw which was very useful) I thought I'd cracked it BUT the problem I am getting is that it keeps stating 'the file is already in the collection' (see below).

Looking at other support articles it states that there must be duplicates of the same tracks, but I have searched a number of tracks that apparently are 'already in the collection', and only 1 item per track (1 track) is appearing. Let's look at the first track in the list of unlocated files, 'blinded' as you can see when I go to the entire rekordbox library and search for the track 'blinded', only 1 comes up, no duplicates;

Can you please advise how to fix this issue? I have been trying to troubleshoot this myself for around 3 hours now, it is incredibly frustrating, especially since I've made no changes to my libraries and yet tracks have magically disappeared and are now not letting me re-locate.

P.S I have rekordbox DJ-RR and have downloaded the latest software today.

Thanks in advance, 

JJ