I experience a problem with expression pedal, no matter if set as volume pedal or set to control volume of output, from time to time (random) it sets the value to 0 so I have to move the pedal to get the actual value and get back the sound. I have EXT2 and EXT3 connected and works good, only built-in pedal having issue. Is this a known error or a hardware issue with the built-in pedal ?