No function when clicking the Download symbol in Menu (Roger Router 2.4.2 flatpak install)

Running Roger Router 2.4.2 installed as a flatpak from your site https://flathub.org/apps/org.tabos.roger following all instructions. Basic functionality including setting up a profile, call listing in main window, and sending fax messages works properly.

Issue description:

When clicking the download symbol from the pulldown menu nothing happens.

When starting on console, an error message is printed after clicking the symbol in GUI.

$ flatpak run org.tabos.roger

(Roger Router:2): Gtk-WARNING **: 13:26:00.654: Can't open portal file chooser: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.portal.Desktop was not provided by any .service files

Nothing besides that is printed.

Program continues without doing anything, closes the menu, does not crash from this, stays usable, and when reopening the menu and clicking the symbol again the error message shows up again in console. You can repeat that unlimited.

Side note: From the symbol it is not clear what is meant to be downloaded. The highlighted Fax message? Or a program update? The symbol has no tooltip, and on your site https://www.tabos.org/projects/rogerrouter/ no hint can be found. Also the default ways of looking up things about a program fail:

$ man roger
Kein Handbucheintrag für roger vorhanden

$ man org.tabos.roger
Kein Handbucheintrag für org.tabos.roger vorhanden

$ flatpak run man org.tabos.roger
Fehler: Ungültige Kennung man: Name muss mindestens 2 Punkte enthalten

Also the help option doesn't contain these pieces of information.

$ flatpak run org.tabos.roger --help

Aufruf:
  Roger Router [OPTION …]
...

System info:

Flatpak version:

$ apt-cache policy flatpak
flatpak:
  Installiert:           1.14.4-1+deb12u1
  Installationskandidat: 1.14.4-1+deb12u1
  Versionstabelle:
 *** 1.14.4-1+deb12u1 500
        500 http://security.debian.org bookworm-security/main amd64 Packages
        100 /var/lib/dpkg/status
     1.14.4-1 500
        500 http://ftp.de.debian.org/debian bookworm/main amd64 Packages

Roger Router version:

$ flatpak run org.tabos.roger --version
Roger Router 2.4.2

OS: antiX 23.1 full runit 64 bit, live, fully apt-upgraded.

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Debian
Description:	Debian GNU/Linux 12 (bookworm)
Release:	12
Codename:	bookworm

Kernel: Linux 6.5.0-0.deb12.4-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.5.10-1~bpo12+1 (2023-11-23) x86_64 GNU/Linux

Session Management: Slimski

$ apt-cache policy slimski
slimski:
  Installiert:           1.5.0-6.0antix8
  Installationskandidat: 1.5.0-6.0antix8
  Versionstabelle:
 *** 1.5.0-6.0antix8 500
        500 https://mirror.23m.com/mx-packages/antix/bookworm bookworm/main amd64 Packages
        100 /var/lib/dpkg/status
     1.5.0-6.0antix4 500
        500 https://mirror.23m.com/mx-packages/antix/bookworm bookworm/nosystemd amd64 Packages

Window Management: IceWM

$ apt-cache policy icewm
icewm:
  Installiert:           3.5.0-1.0antix1
  Installationskandidat: 3.5.0-1.0antix1
  Versionstabelle:
 *** 3.5.0-1.0antix1 500
        500 https://mirror.23m.com/mx-packages/antix/bookworm bookworm/main amd64 Packages
        100 /var/lib/dpkg/status
     3.3.1-1 500
        500 http://ftp.de.debian.org/debian bookworm/main amd64 Packages
     1.8.2-1.0antix2 500
        500 https://mirror.23m.com/mx-packages/antix/bookworm bookworm/nosystemd amd64 Packages