Fixing availability of desktop session type selection

[elfring]

I switched my login interface from the GNOME Display Manager (version 40.1-1.fc34) to the LightDM GTK+ Greeter (version 2.0.8-1.fc34).
Now I am missing the widget for the selection of a desktop session alternative (as it is specified by the setting “indicators” in the file “/etc/lightdm/lightdm-gtk-greeter.conf”).
How should it be reactivated? 🤔

[Apteryks]

Is it wholly missing, or is it there but blank? Using 2.0.8 too, this is what I see:

I have no clue why it occurs, the debug logs don't seem to suggest anything wrong; actually, perhaps this is related (in /var/log/lightdm/seat0-greeter.log:

(lightdm-gtk-greeter:362): Gtk-WARNING **: 18:00:30.082: Drawing a gadget with negative dimensions. Did yo
u forget to allocate a size? (node menubar owner GreeterMenuBar)
DEBUG-Message: 18:00:30.184: Read 8 bytes from daemon
DEBUG-Message: 18:00:30.184: Read 35 bytes from daemon
DEBUG-Message: 18:00:30.184: Prompt user with 1 message(s)

(lightdm-gtk-greeter:362): Gtk-WARNING **: 18:01:01.015: Drawing a gadget with negative dimensions. Did yo
u forget to allocate a size? (node menubar owner GreeterMenuBar)

(lightdm-gtk-greeter:362): Gtk-WARNING **: 18:01:04.754: Drawing a gadget with negative dimensions. Did yo
u forget to allocate a size? (node menubar owner GreeterMenuBar)

(lightdm-gtk-greeter:362): Gtk-WARNING **: 18:01:05.399: Drawing a gadget with negative dimensions. Did yo
u forget to allocate a size? (node menubar owner GreeterMenuBar)
[...]

[Apteryks]

This thread suggests the problem may be a memory allocation failure? https://forums.freebsd.org/threads/lightdm-doesnt-start-automatically-on-boot.73951/. That's odd to me, but the log output are very similar.