[Bug] isBiomeTagSpawnsBlacklist is ignored

[ghost]

Minecraft Version: 1.12.2
Forge Version: 14.23.1.2554
Mod Version: 1.2-10

Just like the title says. To reproduce, set isBiomeTagSpawnsBlacklist to false, create a structure that spawns on the surface with a low rarity, and set biomeTagSpawns to something like "BEACH". Load into a new world and you'll only find that structure on Beach type biomes, instead of the inverse.