Hey Daniel, and welcome!
Looking at the
schematic the switch just adds/removes a cap from the circuit, it's just a make/brake thing.
As I understand it (not being a pro...), the way you have wired the switch the signal bypasses the 470p cap in one position (then the pedal is working) but sends it to ground in the other - so it goes silent.
You need a SPST for this purpose, not a SPDT (although you can use one as well):
Wire SW1 and SW2 to the two lugs of a SPST - or lugs 1 and 2 of a SPDT:
That should fix it imho