(Only on Windows:) Sometimes hitting a shortcut might not work at all. An error message from Workflower will come up, telling you that you need to restart After Effects or your computer. Most of the time, restarting the computer will be necessary. Quite likely, this bug cannot be fixed since it seems to be a bug within the Adobe scripting environment. In these cases, the variable that gives information on the pressed key will not return anything. Unless Adobe isn't fixing this issue, you will need to stick to restarting After Effects or your computer.