[MC1.12.2] "type":"touching" rule is not working

[delta-nos]

MCVersion: 1.12.2
ForgeVersion: 14.23.5.2855
ModVersion: 2.0.15

My json:

{
	"iron_c0":{
		"type":"sphere",
		"stone":"minecraft:air",
		"ore":[{"block":"minecraft:iron_ore", "meta":0}],
		"rules":{"type":"touching", "block":"minecraft:grass"},
		"rarity":4, "count":1, "density":80,
		"min_y":0, "max_y":128,
		"vertical_size":20, "horizontal_size":20,
		"dimensions":[0]
	}
}

Result:

Description:
I think iron ore should be generated only on grass block, but they are generated anywhere. I want to generate ores only cave walls, I tried this json too:

{
	"iron_c0":{
		"type":"sphere",
		"stone":"minecraft:stone",
		"ore":[{"block":"minecraft:iron_ore", "meta":0}],
		"rules":{"type":"touching", "block":"minecraft:air"},
		"rarity":4, "count":1, "density":80,
		"min_y":0, "max_y":128,
		"vertical_size":20, "horizontal_size":20,
		"dimensions":[0]
	}
}

but touching rules are ignored. what should I do.
(If you aren't support MC1.12.2 version yet, I'm so sorry.)