How does Mending work? I was under the impression that as long as you were holding anything with mending on it, it would automatically take the exp and repair it. I'm getting most the exp in levels though and its taking forever to mend my tools. Is this a bug or is that just the way it happens?
Are you wearing armor with mending on it? If so then that is the problem. When the game decides where the xp goes it looks for available mending enchants, regardless of condition, decides what enchant to apply the xp to, and if the item is already at 100% condition it goes into your levels.