Same problem here with my C34 on my ASUS Prime X570-P. Using the button on the case, the LEDs on the front fans work just fine. If I plug my aRGB header into my rear fan, no problems with it's LEDs. But using the motherboard to controll the LEDs won't work. When I connect it to the case controller and the rear fan LEDs don't light and only one of the top fan's LEDs light up, regardless of if the rear fan is connected to the controller board or not. But the one LED that does work will do the effect I select in Armoury Crate. And no matter what is selected, the RAM LEDs work just fine. I just contacted support on the web page and I am hoping to hear back soon...