Enchantments not resetting on the enchantment table after using it

The enchantments offered on the enchantment table do not change, even when other items are enchanted. The only options available are Unbreaking level 1-3. I have applied these enchantments and then removed them using the grindstone multiple times, but I am still only offered unbreaking 1-3. I have broken the enchantment table and rebuilt it, with no avail. 

I am using the bookshelves as recommended in the correct format, and lapis lazuli. My XP level is/was >30. 

I do not have this problem when playing on the PS4, only on iOS.