I think your "toggle silent" action gets executed twice, once in On Touched event and once in On Mouse Click event.
If you are testing on PC, both events are triggered at the same time.
So it toggles off, then on again, that's why nothing happens.
You can set "Use Mouse Input=No" in Touch properties or remove the On Mouse event, and change your code to this:
On Touched button
Set Toggle_music to (Toggle_music=0) <-this will toggle the variable, 0 will become 1, 1 will become 0