In MUSIC section there is not the “FILE” link (just playlist and add-on music) and also I can’t see/navigate the directory where I stored my music (NAS and a pen drive).
I just can navigate NAS directory only with app for Android (YATSE).
Why? How can I solve this bug?
It’s not the first time that it’s happened, but last time I installed OSMC again, but I don’t want to do it again…
Thanks for helping me 
Hello,
I have the same problem, no “file” option or “add music…” under the Music menu.
Select the folder containing your music. Then open the context menu (the “C” key on your keyboard) and add this folder to the Music Librrary. It should scan said folder and you now have a Music Library and the option “File” can be selected too. 