After installing plasma5-bigscreen on a fresh Tumbleweed installation, login
options for both X11 and Wayland show up. However, the desktop environment
fails to start properly. Either of the following can happen (on both X and
Wayland, with no discernible pattern):

1) I get a black screen and a mouse pointer. I am unable to do anything aside
from moving the mouse around.

2) I get the default wallpaper and desktop widgets (home and trash), along with
a digital clock on the middle of the screen. The running apps from a previous
regular Plasma session are also restored. All three widgets are clickable. The
screen edges are also functional. Right-clicking on a blank space on the
wallpaper does nothing.

I can reproduce this behavior on both a VirtualBox VM and an old Thinkpad T420
laptop.