The Last Cross Treasure Hunt (Assassin's Creed: Odyssey)

Hi all. The treasure hunt quest that appeared on Kefalonia began to take place. But I started to pass in the middle of the game, as it turned out after passing it, the spear stops working (((And now the question is if I completely complete this quest and return to the middle of the game, will the spear work again? Or will I have to reload before the last save?