This happened to one of my friends as well. It should have been better specified or the actual interface changed. Why can't there be a separate materials exchange instead of so many useless vendors and characters (the whole north tower, for example)? I've had items that need spirit bloom (legendary) and iron (exotic) though most have needed either helium or spin metal. It's not useless, though you might never need that much. The exchange feature didn't need to be touched at all. All they needed was to ADD the purchase materials feature. But adding seems to be a problem for them. They don't seem to like us playing their "shared" shooter as lone wolves, so they remove things we enjoy playing for. It's as if they removed the selling capacity of properties in Monopoly because players weren't using the renting features and instead were just buying and selling.