I had this working in a previous snapshot prior to you fixing the bug "Game crashes when loading a custom biome / java.lang.UnsupportedOperationException: Trying to add tag of type 8 to list of 10" and my custom village for the jungle would generate just fine so long as I loaded the single biome world first, deleted the region folder, and then added the datapack.

Now, the world loads just fine with the datapack in there but none of the structures generate if I have village_jungle listed in the jungle's biome file's start pool list. If I change it to village_plains, everything works fine. I would like to know why I am suddenly unable to designate a custom village structure feature using the templates you provided.

I have the start pool. I have the template pools. Everything was generating correctly before.