Request for help troubleshooting 4wd unity setup

Hello I am running a 12s lipo setup with 2 unity’s connected by can I followed what I believe to be the correct setup procedure setting them both up individually as master and slave using foxboxes windows tool. then powered down and connected can.

My problem is that one set of motors always seems to be running much slower than the other and only ever gets going about 1/10th speed. I have a 3rd unity that I have tried swapping out as I thought I may have broken something but that did not help. I have also messed with the baud rate to see if that would change it but nothing. Right now I have the pwm signal going into the box that is running slower to try to make sure it wasn’t an issue receiving signal or something.

Anny help or advice is greatly appreciated, thank you.