Ubuntu – Rhythmbox doesn’t add/import MP3s from ~/Music on Ubuntu Gnome 15.04

I just installed Ubuntu Gnome 15.04, all my music is located in /home/user/Music/, e.g. /home/user/Music/Back to The Future.

I run Rhythmbox and try to import all MP3s to the player, but nothing happens. I selected the path /home/user/Music/, but Import x listed tracks remains disabled. I checked the preferences, the parameter Music files are placed in has the right value: file:///home/user/Music. Why can't Rhythmbox just import my MP3s? What should I do in order to see these files inside Rhythmbox library?

All needed codecs are installed already. When I click on MP3-file it's opened with video player and played there. I paid attention that Gnome Music also doesn't display MP3s inside of ~/Music, probably, there is the same root of these two problems.

Execution of

ls -l ~/.local/share/rhythmbox

Returns:

total 132
-rw-rw-r-- 1 user user   1386 May  3 22:20 playlists.xml
-rw-rw-r-- 1 user user      0 May  3 21:31 podcast-timestamp
-rw-rw-r-- 1 user user 129653 May  3 22:16 rhythmdb.xml