Same issue here.
I think that this problem may be noticeable just under certain specific circumstances as the vibration is very subtle.
In my case this is making the pedal useless, in fact it is used to control the same parameter ( a volume fader) that i am controlling via a hand controller.
I need to be able to act on it sometimes with a foot pedal, sometimes with a finger: therefore i have Two different controllers sending the same midivalues.
The footcontroller on the softstep is impossible to use like this as these vibrations are keeping the parameter modulation always active, bringing its value to the centre of the vibration.
Hope this makes sense.
Calibration doesn't fix it.
Different pedals don't fix it, they work fine on other usb ( logidy) or hardware controllers ( novation, gordius, rfx) or hardware processors ( eventide, tc).
It looks like the cc input is too sensitive.
What a pity.
But nice piece of hardware, beside that.