When I put in my BSM modules, I was doing TPMS and parking sensors as well, so ran everything down the LH (driver side in NAR) side of the car; at least one of those, though, has the factory installation running down the RH side of the car - can't remember if it was parking or the BSM.
I did have that same issue, though - Module 3C not getting recognized when I plugged everything in. I even tried a different set of modules (used), but had the same issue. Unfortunately, I can't remember what the resolution was, but it did have to do with wiring because I remember cutting into the harness and using butt-connectors to swap the wires.
Which....now that I'm typing this....I think that it indeed was my running the BSM harness down the driver side that caused the issue.
As
@Cuzoe laid out: If you ran the wiring harness down the driver side of the car, then the "near" connector is connected to the slave controller, but due to wiring differences between the two controllers, that "near" (shorter) connector needs to plug into the master controller. (Wouldn't bet my life on it, but I'm pretty sure the even-numbered module (ends in 6) is the master controller and needs to be where even-numbered parts go - RH side of car).
Pro tip: If you do determine that to be the problem, don't just take the big diagonal cutters to the harness between the modules and cut the whole thing - there are a couple of wires that are the same color and sorting out which brown 0.5mm wire is supposed to go to which on the other side you cut...not fun (at least for a novice wiring diagram reader such as myself). Go one wire at a time.
I would've pulled the wiring harness back and run it the correct way up the RH side of the car, but it was already taped and wrapped to the other two wiring harnesses and tied down to the existing wiring along the sills so that looked like it was going to be way more work.