After upgrading from 5.12 to 5.13 the login screen doesn't show when booting. There's only the mouse cursor showing. Enabling auto-login skips the login screen and I get to the plasma desktop, which works perfectly fine. When locking the session I get the "The lock screen has crashed, use loginctrl..."-message so the lock screen seems to have similar issues. My system has an Nvidia GTX1070 with the proprietary drivers installed. I've tried installing different versions, such as 384, 390, and 396. I've tried moving/clearing ~/.config, ~/.cache, and ~/.Xauthority without luck. I'm not sure where to go from here in order to help with troubleshooting.
Everything seems to work after upgrading to 5.13.1! Setting this to resolved.