Had the same issue with most questlines pre-Shadowkeep. Red War, Osiris, Warmind, Forsaken, the Drifter/Vanguard Allegiance quests, all of them have had their campaign rewards removed. I don't know if it's a bug or intentional but I'm assuming that from the lack of attention, it's intentional. Plus at the end of the Warmind campaign you're supposed to get an exotic armor piece, but you don't get that and in collections the item that you're supposed to get says that it's obtained from a world dropped exotic instead of from the Warmind campaign like before. No clue why they were all removed, I'm assuming it's something to do with the armor 2.0 system that launched with Shadowkeep/New Light, but it sucks for new players or players who are only just now getting into those campaigns.