When I try to use the /enchant command it won't work unless I rejoin the world or use the item.

When I first use the /enchant command it says enchantment succeeded, but it didn't enchant my item, and when I try to use the command again to see if it will enchant it, it will say the following enchantment to the target item, and then it will enchant it when I rejoin the world or use the item.