Thanks to anyone who tried to help.
I bought this controller and the software license for the extra capabilities it offers. I'm familiar with it because I built a machine previously with this same controller without issue.
This is the sixth sixth CNC router I've built. I've used PlanetCNC's hardware and software, the Buildbotics controller and a few different kinds of Arduino-based controllers. I'm not new to the DIY CNC game.
I've realized that in the time I've spent troubleshooting this problem I could have stuck an Arduino on the machine and been cutting already.
Consider this problem solved.
This controller will be on Ebay tomorrow.