Help: Music man Sterling 4 unable to silence Piezo pickup

Hi all, just sent in my sterling 4 with piezo in for a setup after a few years in storage and the techs at the place told me that with the volume knob turned all the way down, and knob panned fully to the piezo, it was still outputting sound.

This doesnt really make send to me cause I remember it being the case where the piezo was affected by the basses active controls which included the volume.

Can anyone with a piezo pick up shed some light if you can get the piezo volume to zero when panned to only the piezo?