This is how i got it working.
I put my music in the Music folder in the raspberry pi.
Edited the Mopidy.conf:
Sudo nano /etc/Mopidy.conf
Changed the line
Media_dir = /var/lib/Mopidy/media
Media_dir = /home/pi/Music
Then found the iP address of the pi
In the terminal type
Then open a browser in a tablet or phone and enter
Where local = the IP address
Once their iris page is up press
Scroll to the bottom of the page and click
Run local scan
Now it will start to scan, but it may take a few minutes depending on the number of files you have in the music folder.
Once it says the scan is completed click
When Mopidy is reconnected click
You should now have the list of folder or tracks.
Let me know if it works for you.