gnome-disk-image-mounter creates loopback device but it is not mounted automatically

[step21]

First I thought nothing at all happened, but it turns out the loopback device is created, only this is not visible as Nautilus hides these by default. When I used nemo though or in Nautilus on 'other places' they are shown and are mounted if clicked on manually. syslog shows that udisksd reports the creation of the corresponding loop device. But this just happens silently and nothing is automounted. If the iso image is clicked again, it just creates anothe loopback device to the same image.
It might also be a Nautilus problem I guess, depending on which part fails here.
I also checked for existing issues here or in gnome-disks upstream, but couldn't find any so maybe it is something about the ubuntu package that could be improved?

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-disk-utility 3.28.3-0ubuntu1~18.04.1
ProcVersionSignature: Ubuntu 4.15.0-34.37-generic 4.15.18
Uname: Linux 4.15.0-34-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.3
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Sep 17 20:50:38 2018
ExecutablePath: /usr/bin/gnome-disk-image-mounter
InstallationDate: Installed on 2014-07-29 (1510 days ago)
InstallationMedia: It
ProcEnviron:
 LANG=de_DE.UTF-8
 TERM=xterm-256color
 SHELL=/bin/bash
 XDG_RUNTIME_DIR=<set>
 PATH=(custom, no user)
SourcePackage: gnome-disk-utility
UpgradeStatus: Upgraded to bionic on 2018-09-07 (10 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Dave Rove (daver1730)]

This bug is still valid in Ubuntu 20.04.

The utility creates the loopback device OK, but the mount sometimes works and sometimes silently fails. This utility has no debug or verbosity option, so there's no way for the end user to give useful information about the failure. That's something that could be remedied first if the devs have no idea why it fails.

[Sebastien Bacher (seb128)]

Could someone having the issue report it upstream on https://gitlab.gnome.org/GNOME/gnome-disk-utility/issues ?