Is 0.5 the actual output of the footswitch or is it the default value of the cc widget in the VCS? If you press the footswitch down and then let it up, does the value go to 0? While it is at 0, you could capture a preset in the VCS and start with that preset selected.
You could also change the Min/Max/Grid of the !cc so the grid is 1. That way it could not take on any intermediate value between 0 and 1. Then do the same thing: capture the footswitch in its OFF state in a preset and make sure that preset is selected when you start the Sound.