Download destiny item manager. The problem is the quest is showing a negative progress and that app will show you how negative your progress is under then progress section and look under quest. You will have to keep getting leaves and converting them to ashes until it is not negative and the quest should work again. Do not collect/spend ashes on your primary character until your quest progresses or it will make it more negative. -400/20 for example can be fixed with 40 leaves. Mine was negative 1300 leaves which made me collect 160 leaves and then convert them to ashes to trigger the quest. Hope this helps. Atleast this was my problem with the quest being bugged.