Maybe check the pedal settings/calibration and the automatic calibration settings in the SPACE system settings…
Check the behavior of the expression pedal output… Does it vary the parameter 0-100% neatly?
Also an ohm-meter (multimeter) will tell you the resistance behavior if you want a sanity check to compare pots, tapers, etc. and whether the resistance track is behaving erratically… which doesn’t seem to be your problem. For example, the Ernie Ball VP Jr varies resistance from 0 ohms heel position (shorted to ground) to 25Kohms resistance when in the toe position.  For your information, I believe the M-Audio EXP is 10K linear pot.