Yes, I have tried to use it by itself and in conjunction with the Shift key, the Fn key, the Alt key and the Ctrl key. Just doesn't do anything. And there seem to be no proprietary drivers for this model on the manufacturer's website. The brand is Red Dragon and it's an inexpensive mechanical keyboard I got on Amazon. I posed this question on Amazon and got the same response from another customer as you gave but it doesn't work for me.
Anyway, if it's just for context menus I find it easier to use the mouse.