mining world

I have a world with final density set to 1 and default block is stone
these are the surface rules
    "type": "minecraft:condition",
    "if_true": {
      "type": "minecraft:vertical_gradient",
      "random_name": "minecraft:bedrock_floor",
      "true_at_and_below": {
        "above_bottom": 0
      },
      "false_at_and_above": {
        "above_bottom": 0
      }
    },
    "then_run": {
      "type": "minecraft:block",
      "result_state": {
        "Name": "bedrock"
      },
      "if_true": {
        "type": "minecraft:stone_depth"
      }
    }
  }
}```
the only time ore is placed is when I used the "ore_iron_upper" placed feature. otherwise I get no iron. the world is 512 blocks high from -256. the biome is fixed to forest and here is the forest.json
```{
  "carvers": {},
  "downfall": 0.8,
  "effects": {
    "fog_color": 12638463,
    "sky_color": 7972607,
    "water_color": 4159204,
    "water_fog_color": 329011
  },
  "features": [
    [],
    [
      "minecraft:lake_lava_underground",
      "minecraft:lake_lava_surface"
    ],
    [],
    [],
    [
      "minecraft:ore_iron_upper",
      "minecraft:ore_redstone",
      "minecraft:ore_redstone_lower",
      "minecraft:ore_copper"
    ],
    [],
    [
      "minecraft:spring_lava"
    ]
  ],
  "has_precipitation": false,
  "spawn_costs": {},
  "spawners": {},
  "temperature": 0.7
}```