I lock my GNOME Shell 18.104.22.168 by Ctrl+Alt+L as usual but when I try to unlock it takes up to a minute before I get my desktop back.
While waiting I get a black background and a mouse pointer.
Any ideas what takes so long?
I had same problem and didn't know how to debug. But I deactivated all gnome shell extensions and then it worked perfectly.
You can deactivate one by one to find out which extension creates the problem—or you deactivate all and activate one by one again ;)