I have the h100i rbg platnium and I have the same issue,
the rbg led on the pump just won't lit up but everything else is working fine, in icue software shows all rbgs are on but in reality only the fan rbgs are on.
From another forum I heared that if you are using adpaters or extension cables for the sata power, then there's not enough voltage to power the led;
however I tried connecting directly from psu to the sata power and the led still won't lit up