Issues after Update to 18.3 on KDE

[borderbridge]

Hello

I am quite new to linux mint. I worked with it now for some time. Yesterday i Updated to "18.3 Sylvia" on KDE.
Now i noticed two issues. I tried to search for them but found nothing that helped me.
Maybe someone can point me towards a solution.

First issue:
When i try to Shutdown my computer via the Shutdown option in the "start menue" nothing happens. Same goes for Log off, restart,.... I click the icon but then nothing happens. Before the update there came a screen coounting down from 30 to 0 seconds then shutting down. or i could shutdown immediately. I can shutdown, reboot through the terminal however.

second:
I Installed SDDM as "login manager" (before the update) If i now navigate to the Systemsettings --> SDDM the systemsettings window just freezes and stops working untill i quit it.

Maybe someone can help me?

Greetings
Borderbridge