I'm using Ubuntu 18.04 with default Cinnamon 3.6.7. I'm using emacs and when I press CTRL-ALT-A, Cinnamon hijacks the keys and does something weird with my terminals.
It bring them all on my current workspace, but there are also some blank ones without anything inside. Pressing again CTRL-ALT-A makes them all disappear.
I can't find what is responsible for this behavior: I've looked into Keyboard/Shortcuts, looked into Cinnamon's code on github without any luck.