MI        This condition is triggered as soon as you have disconnected from the server, regardless of whether the cause was the Disconnect action, the server or other devices along the route.

If your connection is denied, On disconnect will run after a Connection > On connect denied event.

This condition may or may not run if the Client is connecting, but hasn't finished, and you call Actions > Disconnect.

It will not run if you call Actions > Disconnect when the connection is already disconnected, or had never connected.

There are some scenarios where disconnection does not occur, covered under Actions > Disconnect.