Items using the minecraft:wearable component enforce a minecraft:max_stack_size value of 1. This is inconsistent with capabilities used by Vanilla. Notably, the carved pumpkin can be worn in the head slot. Instead of enforcing a stack size limit, Minecraft enforces a stack count of 1 in the head slot.

This discrepancy limits creator capabilities.

Demonstration

The attached image shows this bug at play. A content log error is thrown indicating the problem. In game, the stack limit of 1 is enforced.

The entire code of the offending item is as follows:

{
	"format_version": "1.26.10",
	"minecraft:item": {
		"description": {"identifier": "bug_wearables:custom_item"},
		"components": {
			"minecraft:icon": "helmet",
			"minecraft:max_stack_size": 64,
			"minecraft:wearable": {"slot": "slot.armor.head"}
		}
	}
}

Reproduction

This demo screenshot and code are taken from the behavior pack in the attached world for convenience. This world can be opened (in Minecraft Preview) for inspection or unzipped to access the code associated with such.