https://bugs.winehq.org/show_bug.cgi?id=56087
--- Comment #16 from Olivier F. R. Dierick o.dierick@piezo-forte.be --- (In reply to Olivier F. R. Dierick from comment #15)
$ udisksctl unmount -b "$(/sbin/losetup "path/to/image.iso")"
This should have been (note the addition of '-j' in the command substitution): $ udisksctl unmount -b "$(/sbin/losetup -j "path/to/image.iso")"