Comment # 1 on bug 965517 from Wolfgang Bauer

You are mixing two different things here:
Plasma's lockscreen is totally independent of sddm and its greeter, except that
there's a breeze theme for both.

So is this about the lock screen only?
That's already reported as Bug#964548 and currently under investigation.

Or do you have a problem with sddm (i.e. the *login* screen) too?