[CONFIGURATION] SDDM theme configured by user not used by sddm

[Guest]

Administrator removed for short time SDDM theme from system configuration as prior to that the only theme was presented twice in KDE system configuration which was annoying.
Afterwards SDDM reported obviously error.
Subsequently one SDDM theme was installed again then set to active sddm theme in KDE system configuration.
SDDM however does still not use theme set up by user - some sddm default theam is used instead.
It didn't help to add ThemeDir=<valid user theme path> to /etc/sddm.conf [Themes] group.

Kubuntu 20.04
Plasma 5.18.5
KDE framework 5.68.0
Qt 5.12.8
Kernel 5.4.0.77
SDDM version grabbed from Kubuntu Focal package repository.