Ok, try to re-wording things:
There are two types of expression pedals, which differ by the way they're wired:
#1: (Roland)
Tip: output or control voltage, taken from the wiper of the potentiometer
Ring: input or reference voltage
Sleeve: ground.
#2: (Yamaha)
Tip: input or reference voltage
Ring: output or control voltage, taken from the wiper of the potentiometer
Sleeve: ground.
Here's a link describing it more detailed:https://www.making-sound.co.uk/projects/expression-pedal-meter.html.
The Prophet likes wiring #1. This has the advantage, that you can feed a control voltage from an Eurorack system with a simple Tip/Sleeve cable. That works well and allows you to use an external LFO or sequencer.
So, for the prophet, you need a Roland pedal or you need to modify the wiring. I prefer the Yamaha FC-7, it's easy to to modify and rock solid. But it needs to be re-wired or you need an adapter cable.
Best,
Steffan