Comment # 5 on bug 950893 from Ancor Gonzalez Sosa

Martin, can you paste the content of your
/etc/X11/xorg.conf.d/00-keyboard.conf?

That file is the most important one regarding X11 behavior (unless, of course,
overridden by another file in /etc/x11/xorg.conf.d). The file is regenerated by
systemd in every X11 startup (if it's not there) based on the mappings at
/usr/share/systemd/kbd-model-map.

According to the output of your localectl, the file should be correct, but...