Is the depth knobs set to the maximum value (fully clockwise) when doing your tests? If it is…
Try it in calibration mode to see if both the harmonic mix knob is working and also if the optocouplers are working.
It seems that the analog signal path is working through the pedal but since there is no tremolo effect the LEDs in the optocouplers seem to be on at all times…as if the depth knob is not working somehow (check that the voltage is getting really close to 5V on the center pin of the depth knob). Ensure that the high and low trim pots are set to give maximum LED brightness. You can also check that the LEDs are fully flashing by going through the process described in appendix A.
-Brach