It has nothing to do with H versus L.
There is a good chance that the pot is not wired to the jack in the way it's supposed to be for Moog products. There is no standard for exp. pedals, so Roland/Boss expression pedals are only guaranteed to work with Roland and Boss products. I checked the manual but they don't show a diagram of the wiring (for shame, Boss!).
The Moogs send 5v on the ring of the stereo cable, ground is the sleeve, and the divided voltage (which corresponds to the wiper or center lug on the pot) is on the tip. Boss very well may use a different setup (haven't opened one up) so if this is the case, the only way to use that exp. pedal with the Moog is to rewire the exp. pedal.
You want to connect one outside lug to the sleeve, the other outside lug to the ring, and the wiper/center lug to the tip.