Moving iTunes library and problems encountered

Hello all,

I moved my tuned library onto my Synology Diskstation 214play last night and noticed this morning that some of my newer purchased tunes disappeared. I tried to play a good few of them but they just started re-naming themselves to other songs that I had ripped from CD's.

I did manage to delete most of the purchased songs from the library, even though they couldn't be found/played, and then re-downloaded them from the iTunes store. The songs that had re-named themselves though now seem to be part of the albums that I purchased and i'm not able to re-download the actual file from iTunes store because it thinks its already in the library.

Has anyone encountered this before? I'm not sure if it has something to do with the NAS drive or not but i think that itunes should just say "no the song can't be played because it can't be found" rather than "this song by bob marley will now replace your imagine dragons song".