Space doesn't have a Z knob.

I think you are talking about the H9 and OP is talking about the Space.

Oops, you're right!  Brain glitch!  Ok, OP, can you perhaps provide a little more detail, or even a video of this behavior?  Becuase if it is indeed a Space pedal, this is pretty strange from the way it reads, never heard of anything like this before.  

Also, make sure the Knob Mode (in the System Menu under Utilities) isn't set to Catchup or Locked.