In my minecraft pocket edition survival world, i have a diamond mending pickaxe. It no longer mends. I gain xp, all my other mending tools mend, but my pickaxe is close to breaking. I gain xp all the time, and the pickaxe receives none of it.

My diamond mending pickaxe no longer mends. I receive xp, all my other mending equipment receive xp, but my equipment is close to breaking.