Hello, I'm having a similar issue. I have 2 Boss fv-500h 's which worked perfectly with my M13, I've just bought a hx stomp XL, I get 0-100% wiith exp 1, but 0-99% with exp 2, swapped the 2 bosses over and got the same, tried a different Y cable and now get 0-100 on exp 1 and 2-100 on exp 2... a real issue if trying to control pitches