Hi there, I originally acquired Luna's Howl on my Titan unlocking the Not Forgotten Quest on all characters. I then completed the Not Forgotten Quest on my Warlock while the Luna's Howl Quest was still active. I have now completed the Luna's Howl Quest on my Warlock (to tidy up bounty space/completionist/something to focus on) and it re-awarded the Not Forgotten Quest. A little disappointing that the game doesn't recognise a previous completion on the same character.