Fallback Pool does not seem to be working.

I am trying to use a fallback pool to always put a "roof" on my structure. But I keep having the roofs from the fallback pool not generate. These are the current template pools. They are in the same folder, and the referanced file names are likewise in the same location. Maybe there is a glaring issue in these files or maybe it is something else.
Template pool "worldgen/template_pool/vanilla/towers.json"
{
  "name": "architects_cities:vanilla/towers",
  "fallback": "architects_cities:vanilla/tower_fallback_pool",
  "elements": [
    {
      "weight": 2,
      "element": {
        "element_type": "minecraft:single_pool_element",
        "projection": "rigid",
        "location": "architects_cities:vanilla/towers/tower_fourway",
        "processors": "minecraft:empty"
      }
    },
    {
      "weight": 2,
      "element": {
        "element_type": "minecraft:single_pool_element",
        "projection": "rigid",
        "location": "architects_cities:vanilla/towers/tower_oneway",
        "processors": "minecraft:empty"
      }
    }
  }
}

Template pool "worldgen/template_pool/vanilla/tower_fallback_pool.json"
{
  "name": "architects_cities:vanilla/tower_fallback_pool",
  "fallback": "minecraft:empty",
  "elements": [
    {
      "weight": 0,
      "element": {
        "element_type": "minecraft:single_pool_element",
        "projection": "rigid",
        "location": "architects_cities:vanilla/towers/tower_top",
        "processors": "minecraft:empty"
      }
    }
  ]
}