After changing a pickup today I noticed one wasn't working. Normally I'd just double check to make sure I got everything right. The problem is I changed the neck pickup and the bridge one won't work. When in "RHYTHM" position (Les Paul) the neck pickup works like normal. When in middle "TREBLE" it's like one of the pots is turned to zero. After research, it seemed like the switch would be the problem, but it's not so (I believe).

In the bridge/middle position when the bridge pot is turned to 0 or 10, is silent but from 2 to 9 there is a buzz, leading me to believe it's the pot.

So is the pot the problem? All the wiring is correct. I checked, double checked, triple checked, checked with other people and it is correct.
check the ground lug on the bridge volume pot

Have to taken this pot (the one you suspect is giving you trouble) out of the circuit, and see if it makes a difference. Try running the bridge pickup to the bridge tone, then to the switch as normal, and see if there's any difference with the volume pot bypassed