Comment 3 for bug 1796265

Another addition: The Wayland session turns out to be affected as well, but I wasn't able to figure out the precise reason why this is happening yet.

I have a number of extensions installed, and I could -- for the moment -- fix the problem by switching them all off, except the ubuntu-dock. Then I brought them back one by one, but so far it didn't break again.

When the problem is affecting my system, the lock screen also behaves very strangely. Hitting Super-L first brings me to a screen where I can see my background and the top panel (responsive). Hitting Super-L a second time makes the top panel transparent (I can still see the date and time).

Hitting it a third time brings me to a pure purple screen where I can enter my password. That brings me back to my background and top panel, but without the ubuntu-dock. I have Guake running, but it won't open, neither can I open a gnome terminal with Ctrl+Alt+T. I can do Alt+F2 and try something like gnome-shell -r, but as described before that will end the session (X) or do nothing (Wayland).