I added bug tasks to lubuntu-meta and ubuntu-mate-meta, because it was reported that this is xdg-desktop-portal-gtk misbehaving in these desktop environments, whereas it works fine in GNOME.
For Lubuntu, there is a xdg-desktop-portal-lxqt implementation that appears to solve the problem, so it's just a matter of getting it installed on users' machines.
I added bug tasks to lubuntu-meta and ubuntu-mate-meta, because it was reported that this is xdg-desktop- portal- gtk misbehaving in these desktop environments, whereas it works fine in GNOME.
For Lubuntu, there is a xdg-desktop- portal- lxqt implementation that appears to solve the problem, so it's just a matter of getting it installed on users' machines.
I'm not sure what the solution might be for MATE.