Strange volume pot behavior: VVT with a neck J and bridge MM soapbar

I bought a cheap Rouge 5 string J bass with the intention of messing around and installing a variety of pickups in it.
I installed an Artec MMC5 neck pickup in the bridge position (that's where the string spacing lined up, plus I thought I might get a bassier sound using a neck pup) and the neck pup from an ebay $20 (for the neck+bridge) set. Resistance of the J pup is 6.8K. Don't know the resistance of the Soapbar.
I've got it wired Vol-Vol-Tone with 250K pots.

The behavior is this:
When I use the pots one at a time (one pot turned all the way down), the behavior is normal.
When I try to combine the two volume pots it gets weird. If pot A is all the way up, bringing pot B up does nothing until above 75% then the output drastically lowers.
Lowering pot A below 75% then drastically increases the output of pot/pickup B. In effect, I can only use one pickup at a time.
I can't seem to get any combination of the pickups.
Can anyone provide any insight here?

 

Ah yea, I meant the word akin to brigands, not ladies facepowder.
swapping the leads coming from the pickup, or swapping the leg connections on one of the pots?
attached is a quick sketch of the wiring set-up.