Simple_form saving values as nil and not displaying anything on index

I'm making a web app to track ideas that are within categories. The categories are saving fine, but the ideas that belong to the categories are not. The ideas are also visible on show, but not index. I tried switching up the idea_params so they don't have the permit, because when it did it gave me a missing param error.

IdeasController

def index
    @ideas = policy_scope(Idea)
    # @ideas = Idea.all
  end

  def new
    @idea = Idea.new(idea_params)
    authorize @idea
  end

  def create
    @idea = Idea.new(idea_params)
    @idea.category = @category
    @idea.user = current_user
    authorize @idea
    if @idea.save
      redirect_to category_ideas_path(@category)
    else
      render :new
    end
  end

  def show
    authorize @idea
  end

  private

  def find_category
    @category = Category.find(params[:category_id])
  end

  # def find_user
  #   @user = current_user.id
  # end

  def idea_params
    params.permit(:title, :description, :status, :category_id)
    # params.require(:idea).permit(:title, :description, :status, :category_id)
  end

Idea Index

<ul>
  <% if @category.ideas.nil? %>
    <p>Start adding ideas</p>
  <% else %>
    <% @category.ideas.each do |idea| %>
      <li>
        <h1> <%= idea.title %> </h1>
        <p> <%= idea.description %> </p>
      </li>
    <% end %>
  <% end %>
</ul>

Idea New

  <div class="form-inputs">
    <%= f.input :title %>
    <%= f.input :description %>
    <%= f.input :status, priority: ['incomplete'], collection: [ "incomplete", "in progress", "done"]  %>
  </div>

  <div class="form-actions">
    <%= f.button :submit, class:'btn btn-outline-primary'  %>
  </div>
<% end %>

Idea Model

class Idea < ApplicationRecord
  belongs_to :category
  belongs_to :user
  validates :title, presence: { message: 'Cannot be blank' }
end

Idea Category Model

class IdeaCategory < ApplicationRecord
  belongs_to :idea
  belongs_to :category
  has_many :ideas, through: :idea_categories
end

Category Model

class Category < ApplicationRecord
  has_many :idea_categories, dependent: :destroy
  has_many :ideas, through: :idea_categories, source: :idea
  belongs_to :user
end