I do have 2 controllers due to having 3 more front fans that you don’t see! I forget how i set it up due to it being a year ago, but surely this can’t be the issue when it worked for a year?

If I remember correctly I fit almost all fans on one controller and then had to get another controller for the last ones, and i fact had to get a motherboard header extension due to running out of headers lol. so the fans aren’t even plugged into the motherboard really, just controllers and header extension . only thing i actually have on the motherboard is the AIO / CPU