Congratulations for your software!
I’ve the same problem of a similar Topic. Mine is little different.
I tried to attach a UBS3 HDD disc (no ssd) to Raspberry Pi3.
I’m a Linux user so a formatted this HDD in ext4 (but I don’t think this is the problem)
The hdd is well mounted as I checked in console (under /media …) and folders& files are visible but in Volumio webpage it is not visible.
The HDD is good and I’ve unmounted it before attaching into Pi3.
any solutions ?
PS I’m Italian and, in particular, I’m ‘fiorentino’ too. Is there any forum, or the way to contact you, in our language?