custom model data help

why is the carved pumpkin invisible when it has no custom model data?
  "model": {
    "type": "minecraft:model",
    "model": "minecraft:item/carved_pumpkin/helm",
    "tints": []
  },
    "overrides":
  [
    { "predicate": { "custom_model_data": 2}, "model": "minecraft:item/carved_pumpkin"}
  ]
}```