SLE301 lab 1-1 ctl-alt-del change not working

Using SLE301 Lab manual

1- 1 Using the YaST Security Module
11.On the left, select Boot Settings
12.From the Interpretation of Ctrl + Alt + Del drop-down list select:

This works as expected, c-a-d now shows a shutdown popup.

19.From the YaST Security Settings from the right select Boot Menu Settings to change the setting for Ctrl+Alt+Del to: Ignore
This changes
/etc/systemd/system/ → /usr/lib/systemd/system/
to :
/etc/systemd/system/ → /dev/null

But this does not change the ctrl-alt-del behaviour, it still gives the shutdown popup.

What is missing for this to work as described in the exercise ?

Rgds, Eirikur.