I have music stored in several folders below /data/INTERNAL and I have created several radio station favorites.
The following frequently happens on Volumio 2.163:
No stations are shown in “favorite radios” and no music is shown in “music library”. It doesn’t help to reload the web page. If I ssh to volumio, I can see the music in /data/INTERNAL.
Music and radio stations show up again after reboot.
This is what I see right now: 
It appears that the RPi 3 randomly loses the wifi connection, although I deactivated wlan powersave.
Hi Folks
Yes, I experienced the same issue with my ODROID C2.
This occurs in my case if I want to play something Volumio can’t reacht, for example an Internet Radio Station.
If you open a SSH session and restart mpd service (service mpd restart) everything is back online again.
This looks to me like a timeout problem.
Maybe someone knows where to change that?
Hope I could help
patrik