Comment # 13 on bug 1001554 from Kunigumi yen

I also got same problem when I upgrade to Tumbleweed 20160927 (Gnome 3.20 to
3.22).
A user umount (or eject via Nautilus) the external device it not work, unless
use gnome-disks or root user.
Today up to Tumbleweed 20161003, the problem persists.