I don't know what's causing it; in the previous update, it was working perfectly fine.
"format_version": "1.13.0",
"minecraft:feature_rules": {
"description": {
"identifier": "minecraft:soulcreeper_feature_rules",
"places_feature": "minecraft:soulcreeper_mcstructure"
},
"conditions": {
"placement_pass": "surface_pass",
"minecraft:biome_filter": [
{
"test": "has_biome_tag",
"operator": "==",
"value": "soulsand_valley"
}
]
},
"distribution": {
"iterations": 1,
"scatter_chance": {
"numerator": 2,
"denominator": 6
},
"x": {
"distribution": "uniform",
"extent": [ 0, 16 ]
},
"y": {
"distribution": "uniform",
"extent": [ 0, 124 ]
},
"z": {
"distribution": "uniform",
"extent": [ 0, 16 ]
}
}
}
}