Rails - has_many through, STI, and scope

I have the following models:

    create_table :production_actions do |t|
      t.string :name
      t.string :key
    end

    create_table :production_attributes do |t|
      t.string :name
      t.string :key
      t.string :type
    end

    create_table :production_items do |t|
      t.timestamps
    end

    create_table :line_items_production_items do |t|
      t.references :line_item, null: false
      t.references :production_item, null: false
    end
    add_index(:line_items_production_items, [:line_item_id, :production_item_id], unique: true, name: 'line_items_production_items_unique')

    create_table :production_attributes_production_items do |t|
      t.references :production_attribute, null: false, index: {name: 'production_items_on_production_attribute_id'}
      t.references :production_item, null: false, index: {name: 'production_attributes_on_production_item_id'}
    end
    add_index(:production_attributes_production_items, [:production_attribute_id, :production_item_id], unique: true, name: 'production_attributes_production_items_unique')

    create_table :production_actions_production_items do |t|
      t.references :production_action, null: false, index: {name: 'production_items_on_production_action_id'}
      t.references :production_item, null: false, index: {name: 'production_actions_on_production_item_id'}
    end
    add_index(:production_actions_production_items, [:production_action_id, :production_item_id], unique: true, name: 'production_actions_production_items_unique')

  class ProductionAttributeProductionItem < ApplicationRecord
    belongs_to :production_attribute, class_name: "ProductionAttribute::Base"
    belongs_to :production_item, class_name: "ProductionItem::Base"
  end

  module ProductionItem
    class Base < ApplicationRecord
      self.table_name = "production_items"

      has_many :production_attribute_production_items, class_name: "ProductionAttributeProductionItem"
      has_many :production_attributes, class_name: "ProductionAttribute::Base", through: :production_attribute_production_items

  end

  module ProductionAttribute
    class Base < ApplicationRecord
      self.table_name = "production_attributes"


    end
  end

  module ProductionAttribute
    class PaperType < ProductionAttribute::Base

    end
  end

  module ProductionItem
    class Paper < ProductionItem::Base
              has_one :paper_type, -> { where(type: "ProductionAttribute::PaperType")},
                class_name: "ProductionAttribute::PaperType", foreign_key: :product_attribute_id,
                through: :production_attributes, inverse_of: :product_attribute

    end
  end

There are many types of production_items that are all saved in a table via STI. There are also many types of production_attributes all saved in a table via STI. A production_item has (and belongs to) many production_attributes. Based off the subclass, i want to create specific product_attribute associations based off the type of production_item. for instance, a paper production_item will have a paper_type product_attribute.

my problem is i am trying to get the specific scoped associations like paper.paper_type to work but i am having a hard time. If i do something like the following i get an error:

[1] pry(main)> p = ProductionItem::Paper.new
   (0.3ms)  SET NAMES utf8,  @@SESSION.sql_mode = CONCAT(CONCAT(@@sql_mode, ',STRICT_ALL_TABLES'), ',NO_AUTO_VALUE_ON_ZERO'),  @@SESSION.sql_auto_is_null = 0, @@SESSION.wait_timeout = 2147483
=> #<ProductionItem::Paper:0x00005602a669b528
 id: nil,
 created_at: nil,
 updated_at: nil>
[2] pry(main)> p.paper_type
ActiveRecord::HasManyThroughSourceAssociationNotFoundError: Could not find the source association(s) "paper_type" or :paper_type in model ProductionAttribute::Base. Try 'has_many :paper_type, :through => :production_attributes, :source => <name>'. Is it one of jobs?
from /home/USERNAME/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/activerecord-5.2.4.4/lib/active_record/reflection.rb:920:in `check_validity!'

Ive tried a few things without any luck. any idea why this isnt working?