This been happening to me once every few days or so, for the last several months. It's rather bizarre.
Sometimes the Alt+Tab window switcher gets weird and it no longer switches windows on the first Alt+Tab. It just highlights the current window, and I need to press Alt+Tab+Tab instead to actually switch the window.
It always returns itself to normal behaviour after 5~30 minutes.
My current setup:
- Ubuntu 18.04.2 LTS
- Settings > Devices > Keyboard > Switch Windows > Alt + Tab
- Not sure if relevant, but I usually have a Notepadqq window open.
Why is this happening, and how do I make it stop?