Hm, then there must be some pre-quests that you didn't made. But I couldn't find out what for pre-quests they are, except the courage stone. But I bet you did it already. One thing that I am sure that it is not a bug or something. I can remember that I couldn't ask the mystic old man for more quest, until I visited the Revival Isle's volcano and saw there an nest with eggs. And then I asked my friends what for they are, they told me that I must visit the mystic old man in Holy Village again. I went directly to that old man and tried to ask him again. I was surprised that he had one more quest for me.