Sorry to bump in but I ran into a somewhat similar issue with a combination of PC 3.0 and CEX. Basically the Main LED and Channel 1 Work but Channel 2 does not. I got around it since I'm running a quad rebel with all the same color and having Channel 1 and main each drive 2 LEDs via serial, but I can say that something seems not to be working on channel 2. I've got a splitting headache at the moment but I'll take some photos tomorrow and shoot a message to Erv on the FX-sabers board and ask if those might help track down what could be happening. Many thanks for trying to track down your problem, document it and sharing the information. It is really appreciated and it really does help.