The bug

/item entity <targets> <slot> modify <modifier> does not work when the resulting item has a different item ID.

Affected loot item functions

• minecraft:enchant_with_levels (1)
• minecraft:enchant_randomly (1)
• minecraft:set_enchantments (1)
• minecraft:furnace_smelt
• minecraft:exploration_map

(1) Only applies for books

How to reproduce

1. /item entity @s hotbar.0 replace minecraft:porkchop

2. /item entity @s hotbar.0 modify mc-205321:furnace_smelt

   → Replaced a slot on … with [Cooked Porkchop], but the item is still Raw Porkchop.

{
    "function": "minecraft:furnace_smelt"
}