Please note that Siffow's list of known issues mentions that several DLC1 (The Dark Below) and DLC2 (House of Wolves) cards, including mission and enemy cards, are now appearing locked or not unlocking for some players. Unless I am mistaken, Rise of Crota was the mission you would complete after killing the hive knight ultra, Urzok the Hated, in the Urn of Sacrifice quest chain. In year one, this mission node only appeared once and disappeared upon completion, unless you deleted the bounty from your inventory before completion and subsequently completed the mission before returning to orbit. Enemies>Hive Exalted>The Forsaken was the other card associated with this mission node. Without direct intervention by Bungie to correct the issue, I do not think there is anything you can presently do to obtain the card.