Boss SYB-5 Synth on guitar (with expression) (without talking)

A guitar loop going through all the modes the pedal delivers. As you will notice, on guitar the tracking is ok... until you reach the C on the E string ! Past that point unexpected sounds may occur ! Signal is Jamman solo XT - boss SYB-5 - Victory The Jack clean channel. Jamman external controller and expression knob are homemade.