Empowered rend negates Charged staff effect

I have noticed using power charge on rend for the empowered buff, negates the slashing waves on charged staff regardless if charged staff is active before or activated after the usage. Either this is not intended to wok together which i do not see a reason for or it is a bug but the two being used together means charged staff will b active but even after rend loses its empower charged staff remains broken!!.