It looks to be a problem with that page. There are non-breaking space characters between the arguments in that command, instead of regular space characters. I think if you copy the command from that page it will not work. Try running the command copied from here:
I got it working
After looking at the link in LibreOffice I did see those special space characters and changed them.
Then I ran flatpak run org.gnome.Shotwell//master
Now it opens up but it is also very slow. It hesitate about 10 sec, when ever you try anything.
Can’t seem to find anything in the system logs that indicates a problem. Except for this line
in the terminal when starting
(shotwell:2): GLib-GIO-WARNING **: 02:12:49.383: Can’t find module ‘dconf’ specified in GSETTINGS_BACKEND
flatpak run --nodevice=all --devel --command=sh org.gnome.Shotwell
Did get a few errors
Starting program: /app/bin/shotwell
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff2d42640 (LWP 17)]
[New Thread 0x7ffff2541640 (LWP 18)]
[New Thread 0x7ffff1d40640 (LWP 19)]
Gtk-Message: 15:12:54.607: Failed to load module "xapp-gtk3-module"
** Message: 15:12:54.622: main.vala:429: Starting session with system profile
(shotwell:14): GLib-GIO-WARNING **: 15:12:55.891: Can't find module 'dconf' specified in GSETTINGS_BACKEND
[New Thread 0x7fffde292640 (LWP 20)]
[New Thread 0x7fffdda91640 (LWP 21)]
[New Thread 0x7fffdd290640 (LWP 22)]
[New Thread 0x7fffdca8f640 (LWP 23)]
[New Thread 0x7fffcffff640 (LWP 24)]
[New Thread 0x7fffcf7fe640 (LWP 25)]
[New Thread 0x7fffceffd640 (LWP 26)]
[New Thread 0x7fffce7fc640 (LWP 27)]
[Detaching after fork from child process 28]
[Detaching after fork from child process 32]
But the delay is now gone.
So according to this its some kind of USB issue on Oct 20 222 msmeissn** commented
libusb called by libgphoto2 hangs when opening /dev/bus/usb/xxx/yyy device. If it is stuck in open() directly, it might indicate a kernel issue or a locking issue.
I have no idea how to go forward now
When importing photo I do get this error. It can still import from my usb drives HMMMM, do get this error
GVFS-WARNING **: 15:25:08.581: The peer-to-peer connection failed: Error when getting information for file “/run/user/1000/gvfsd”: No such file or directory. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.