Minecraft wiki entry for Loyalty, associated text: When the player is traveling between dimensions, the trident attempts to return to the player but stays in the current dimension. For example, if a player throws a Loyalty-enchanted trident while in the nether and goes to the overworld before the trident returns, the trident stays in the nether and does not despawn. As soon as the player returns to the nether, the trident resumes returning to the player.