Syncing Corsair Commander Cores

My rear fan RGB stopped working when it was connected to a Corsair RGB hub. I originally had one RGB hub and one Corsair Commander Core. I bought a Corsair Commander Core XT over the weekend to replace the RGB hub and I installed it. It partly fixed it because my rear fan now lights up in white, but OpenRGB hasn't been able to detect the rear fan RGB yet. I haven't been able to control the fan RGB and change the color as a result. I did not connect the Commander Cores up to each other yet. The Commander Core XT has an optional 3 pin RGB C header and one USB 2.0 headers that I did not connect up. Should I try connecting either of those from the XT to the other Commander Core?