jigsaw structure in the nether

[spice salmon]

im trying to generate a jigsaw structure in the nether but it keeps saying its out of bounds. i tried changing stuff around but nothing seems to work. the structure is 29x10x29 so its not too big.

    "format_version": "1.21.100",
    "minecraft:jigsaw": {
        "description": {
            "identifier": "cata:monolith_trial"
        },
        "step": "underground_structures",
        "terrain_adaptation": "none",
        "start_pool": "cata:monolith_trials",
        "max_depth": 1,
        "heightmap_projection": "ocean_floor",
        "biome_filters": {
            "test": "has_biome_tag",
            "operator": "==",
            "value": "nether"
        },
        "start_height": {
            "type": "constant",
            "value": {
                "absolute": 30
            }
        }
    }
}```