I'm not exactly an advanced player, but it seems
like this should be one of those "polarity flip" things - I take a maker down there, release AC onto the 2147M spot, it goes red, hits the 2147M regular creeper, flips -that-, and lets you get through.
The problem is that when I release the AC, the spot goes to... -2147M good creeper. If you can't reproduce it, let me know and I'll snag a screenshot (or even a save) for you.
... that said, it's entirely possible I'm on the wrong track, in which case I wouldn't mind help.
Edit: On a whim, I decided to charge with AC and burst it rather than just producing the AC. Flipped it exactly as expected.