Linking local files to catgalogue

[conradkun]

So I've had local files for a long time, and I could add them in my library as music linked to the Spotify catalogue just as usual, but today I started cleaning up a bit (I had the same album split into two different parts, etc...) and when I tried to put the album up again in my library I didn't have the option (the '+' sign) so I was not able to do it. What has changed and how can I fix it? If it is of any help, the music involved is early Blind Guardian and Children of Bodom albums.

Thanks in advance!