Ubuntu Desktop 20.04.1 LTS
For example if I open the Terminal app the Terminal window doesn't appear but the mouse pointer does change to a cursor when hovering over the area of the desktop where the terminal window should be.
The mouse pointer can still be moved around the screen but clicking has no effect.
Keyboard shortcuts like Alt + Tab do not work.
Tried the following but these have not resolved the problem:
sudo apt install --reinstall gnome-shell
sudo apt purge gnome-shell
sudo apt install gnome-shell