Definitely fair enough 
I continued some troubleshooting and ended up figuring out that there must’ve been a film of some sort deposited on one of my washers that, whatever it was, wasn’t cleaning off with just alcohol. I manually positioned and tested the nozzle against the washers using the M119 command in the terminal to report if z-min was triggered or not, and all but the one were very consistent (thus suggesting it’s on the washer’s end vs. the print head). After checking and double checking the continuity of the hookups, I finally tried cleaning the washer with some DeoxIT contact cleaner – getting some pretty solid first layers now and no longer observing the probe anomaly!
While it wasn’t ultimately helpful in resolving the issue for me, there were some useful tidbits in this thread (in case someone lands here trying to troubleshoot their unique woes):
I did end up going into the electrical box on mine in my desperation, and found that there were some very precarious connections due to the adhesive cable anchors they use for the assembly becoming unstuck and dislodged. I imagine it was only a matter of time that the resulting tension on the wires in conjunction with vibrations during printing might have caused an even bigger headache for me down the line 
I repositioned some of the wires to relieve this, giving up on the anchors entirely.
Anyway – thanks for the response, @scotchtape! Your remedy for what seems to be a poor system design seems to be working for you, so I might call it a simple solution to an overly complex problem over a stupid hack
Be well!