I’d like to share my experience after a fresh installation of KDE 44 and the solution I found for enabling Num Lock on the login screen. Plasma Display Manager is used by default, and the SDDM solution no longer works, or rather, it needs to be modified. Here’s the SDDM solution.
I modified for the Plasma Display Manager the entries as follows:
a) in the file /etc/plasmalogin.conf under the entry
[General]
Numlock=on
b) in the file var/lib/plasmalogin/.config/kdedefaults/kcminputrc add a new entry
[Keyboard]
NumLock=0
c) If Num Lock should be enabled while working with KDE, the option “Number pad on Plasma startup” must be set to “Enabled” under System Preferences - Keyboard.
I hope someone finds this post helpful.