The Unbreaking Enchantment is never at the bottom of the list

When i use an anvil to combine enchantments or use an enchanted book on a tool the unbreaking enchantment is not shown at the bottom no matter how many ways you do it. It used to do it in past versions. This is a screenshot of what im talking about. The unbreaking enchantment is always the second or third one never the last one even when it should be.