Twangabilly

I have been having this same issue on my Squier Bass VI and turns out sometimes a way to fix it is to move the bridge either back or forth towards the neck or tremolo end. The bridge posts are too small for the holes in the body (which is a pretty terrible design as it means intonation can easily be changed by accident). No need to detune, just give the bridge a firm shove with your thumb. I think the ground wire must also be connected to there, as when I nudged the bridge further towards the neck, I then found the noise went a LOT, and if I touched the strings etc, then it would cancel out the expected normal quiet background noise. Beforehand I could only do it by touching the pickup selector plate, or the plate with the jack/knobs on like you’ve described. I think the only solution is going to be to buy a new bridge with larger mounting poles, or find some metal sleeves to bridge the gap, while still making contact to the ground wire…