https://forums.highrez.co.uk/viewtopic.php?t=4974

It is possible for the button state to get stuck, causing Windows to ignore button presses.

When chording is enabled, and Cancel by time AND/OR by movement) is enabled, when a chord is cancelled and it simulates the button down, it is possible for the button UP to happen BEFORE the simulated input is processed (as it runs in a different thread).

In this case, Windows recieves the button UP before the button DOWN. Thus it thinks a button is held down, and other buttons do not work as expected.

If the button down is simulated, the button up should also be simulated, to ensure it will not come in out of order!