It's bugged, like usual same thing every time cause Bungie for whatever reason cannot learn from their mistakes. In this repeated mistake, you have to go to the portal, then select Crucible, then select heavy metal from there. Same thing happened to me, if you try to launch elsewhere you wont get progress to the quest and this option was the only one that actually dropped T4's, the loot in when launched from the tower was nothing after 2 runs and 3rd one gave me crappy T2... I am 430 guardian rank 9 so that shouldn't be happening. You are not alone with this missed bug by Bungie