@FreeMan was graphus in the room lately? Unless the user has been in the room in the last 14 days, they won't get pinged when you put @ before their username.
I'm well aware of that, @NikeDattani. I pinged him in a follow up comment to the one I linked because of that fact. Unfortunately, he flat refuses to participate here.
Thanks for making sure I was aware of the situation, though.