Do you have a star point or star ground? I fought noise issues in my limit switches for a long time until I connected the VE- (in my case off of the cap of my power supply to the star point also along with the earth ground). Prior to that single connection, I had tried everything, capacitors, resistors connecting the shields at one and or both ends or none at all. Nothing helped until that wire was connected. Now that that wire is connected, the shields dont seem to matter ( I do have them connected to the star point only, but I tested them without just out of curiousity). I have laid the limit wires close to stepper and power wires while running code, no errors. I am running a debounce of 100. I could probably go less but that should stop any stray signals. Btw I never could see the triggering on the diagnostics page unless I was statically testing the switch circuits.