I may have a partial solution. I have the c36 and an ASUS b550-f and like you, my front case fans would not sync properly. Only half of 1 fan would sync.
Solution: In the armoury crate software go into the motherboard section. Click "addressable headers" where it says number of LEDs, 1 is default. Change that to 2 or higher and all the lights on the fans will work as intended. I set my number to 100. I read somewhere that there were 90 LEDs or so in the fans. So 100 seemed to fit.
Hopefully this is the answer you were looking for. Im scrolling through all of the forums that I browsed trying to find an answer and trying to pass on my discovery to anyone and everyone as I never did find a solution outside of purchasing a splitter.
