I can confirm that removing the dbus-user-session and reverting a workaround (calling the gnome-keyring-daemon --replace --foreground) solved the issue. There was no xdg-desktop-portal or xdg-desktop-portal-gtk packages in my case. I suppose the dbus-user-session was installed with the flatpak. Ubuntu 16.04.2 LTS
I can confirm that removing the dbus-user-session and reverting a workaround (calling the gnome-keyring- daemon --replace --foreground) solved the issue. There was no xdg-desktop-portal or xdg-desktop- portal- gtk packages in my case. I suppose the dbus-user-session was installed with the flatpak. Ubuntu 16.04.2 LTS