Items which use entity models will not render another entity model if specified via item model component

The bug

If, via commands, one item that renders as an entity has an item model specified that should have it render as a different entity, it will not render as the entity specified for the item model component, instead rendering the one associated with the base item's ID.

How to reproduce

1. /give @s chest[item_model="minecraft:stone"]

2. /give @s shulker_box[item_model="minecraft:stone"]

3. /give @s chest[item_model="minecraft:shulker_box"]

4. /give @s shulker_box[item_model="minecraft:chest"]

Expected results

In order we'd get: a chest whose item form looks like stone, a shulker box whose item form looks like stone, a chest whose item form looks like a shulker box, and a shulker box whose item form looks like a chest.

Actual results

The first two are as expected. However, for the last two, the chest still looks like a chest and the shulker box still looks like a shulker box.