Just got mine today and when I plugged it in the WASD and direction keys were lit up. Well now they aren't and the button that controls them isn't working. WTF!!!
It could be countless issues. The keyboard is a little new so it might take time to figure it out. It could be almost anything. Defective board, driver issue, software issue, firmware issue , might need to change which usb plug you are using etc. Could almost be anything. Contact logitech support or try testing it on another computer for example.