Disappearing enchantments on item in chest in Nether

I left my enchanted diamond pickaxe (fortune III, efficiency III unbreaking II) in a chest in the nether as we’re using it extensively on this map to get around. That was the safest place I could leave it at the time. Or so I thought. Went to pick it up today and the enchantments are all gone. Same amount of wear on the pickaxe, found in the same position. It had been in there for a few real time days with no problems before with frequent play.