ISSUE SOLVED.
This was the weirdest problem ever. Timeline:
1. I buy a KC60, program it with TKG. EZPZ, fully functional.
2. I buy a GH60. Plug it in, then KC60 does not work anymore after that.
3. I panic, try reflashing and updating firmware on the kC60a million times. No dice.
4. Eventually, I figure that I should just give up and program the GH60 and use that instead.
5. I program the GH60 successfully. When I plug the KC60 back in, it works!
Looks like the issue may have been that for some reason my PC was thinking my KC60 was the GH60 (unflashed), as the KC was showing up as a GH in the Device Manager. No number of driver updates or other ****ery worked. I just had to "de-scramble" the Device Manager by fully flashing both boards. Weird.~~~~