I unlocked NG+ and did the necessary things to collect the black shards. Sometime throughout my runs getting the black shards. The End shard appeared in the bar and I clicked the button. This triggered the ending scene, however, since I didn't complete all the side quests, it didn't load and told me to come back. Problem is, the button on the tombstone does nothing even when I collect the 10 shards it needs. I don't want to reset the entirety of my progress... If I have too, then oof.