Hi, I just bought a new PRS Paul's Guitar SE yesterday. As soon as I got home, I plugged it in and was disappointed to hear that humm/buzz noise you get when something is not grounded properly on a guitar. I did some troubleshooting and found that the ground wire they tried installing between the stop tail post insert and the tone knob casing was not making proper contact at the stop tail post. I fixed the problem by carefully pulling out the ground wire that was in the hole going toward the stop tail post, and screwed in a small screw in the hole until it started touching the post. I then backed off the screw a bit, stripped and wound the original ground wire to the screw then screw the screw back in until it made good contact with the post. The guitar is as quiet as any other of my guitars now, thankfully. In hindsight, I probably should have had this done on warranty, but I didn't want to spend my time bringing the guitar back and trying to explain all the details to some clerk who may or may not know what grounding does in a guitar.
From the pictures I'm seeing of your electronics, I can't seem to locate the ground wire going to the bridge or stop tail post to the back of one of the pots... and this ground connection to the stop tail is not shown in the PRS wiring diagram either. A quick test for you would be to set a multimeter to test continuity and touch one lead to the bridge and the other to the back of the tone or volume pot. If you don't get continuity, that's your problem. You bridge is not grounded. Another test, if you don't have a meter; when you have your guitar plugged in, does the humm/buzz get worse when you touch the strings and bridge, or does it diminish? If the noise gets louder, your bridge is not grounded.
In any case, good luck and let me know the results if you try any of these recommendations.
Cheers,
Phil