[1.21.3pre6] Custom CIT Models for Paintings broken if Parent Model used

[UnduGT]

Description of Issue

Custom Models for Paintings are broken and show a missing Model when the Model uses a parent Model.
Update: Still present in 1.21.3 pre7

Steps to Reproduce

1. Use Custom Resource Pack that changes the model property in CIT of Paintings
2. The Custom Model should use a parent

OptiFine Version

OptiFine 1.21.3 HD J2 pre5
OptiFine 1.21.3 HD J2 pre6
OptiFine 1.21.3 HD J2 pre7

Installation Method

Default Installer

Additional Information

Changing the Model value to a vanilla model, for example acacia door loads the Vanilla Painting Model instead of the purple-black one

Example Painting Albanian

alban.properties:

type=item
matchItems=painting
model=optifine/cit/items/paintings/alban.json
components.minecraft\:entity_data.variant=minecraft:alban

alban.json:

{
    "parent": "optifine/cit/items/paintings/models/painting1x1",
    "textures": {
        "front": "item/painting/alban"
    }
}

painting1x1.json:

{
	"credit": "Created by UnduGT for the Undopia Patch",
	"textures": {
		"back": "minecraft:item/painting/painting_back"
	},
	"elements": [
		{
			"from": [0, 0, 7.5],
			"to": [16, 16, 8.5],
			"faces": {
				"north": {"uv": [0, 0, 16, 16], "texture": "#front"},
				"east": {"uv": [0, 0, 1, 16], "texture": "#back"},
				"south": {"uv": [0, 0, 16, 16], "texture": "#back"},
				"west": {"uv": [0, 0, 1, 16], "texture": "#back"},
				"up": {"uv": [16, 0, 0, 1], "texture": "#back"},
				"down": {"uv": [16, 0, 0, 1], "texture": "#back"}
			}
		}
	],
	"gui_light": "front",
	"display": {
		"thirdperson_righthand": {
			"rotation": [0, 90, 0],
			"translation": [0, 0.75, 0],
			"scale": [0.375, 0.375, 0.375]
		},
		"thirdperson_lefthand": {
			"rotation": [0, 90, 0],
			"translation": [0, 0.75, 0],
			"scale": [0.375, 0.375, 0.375]
		},
		"firstperson_righthand": {
			"rotation": [0, 135, 0],
			"translation": [0, 1.5, 0],
			"scale": [0.4, 0.4, 0.4]
		},
		"firstperson_lefthand": {
			"rotation": [0, 135, 0],
			"translation": [0, 1.5, 0],
			"scale": [0.4, 0.4, 0.4]
		},
		"ground": {
			"translation": [0, 3, 0],
			"scale": [0.25, 0.25, 0.25]
		},
		"gui": {
			"rotation": [0, 180, 0],
			"scale": [0.9, 0.9, 0.9]
		}
	}
}

Ingame: