postしてもモデルにデータがsaveできない

前提・実現したいこと

Railsでwebサービスを作っています。
userのサインアップが完了した（usersモデルにデータをsaveした）後に、そのuserの詳細データを入力させuserモデルとは別のDetailsモデルにsaveする機能を作っています。（下述するuserコントローラのコードを読んで頂いた方が、実現したいことが分かりやすいかもしれません）

デバッグを見ると必要なDetailsの項目とそれに対応する値は送信できているようです。

Debug
1--- !ruby/object:ActionController::Parameters
2parameters: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
3  authenticity_token: NdZE8VVVUbEafANhWLU+UqQcF6Ipk99Gc0I8SO1mvts1JOWW/dXBDUUEhsjU2ujNNUw/GWIgg==
4  mother_tongue: Japanese
5  japanese_level: Capable of daily conversation | 日常会話ができる
6  gender: he/him | 男性
7  region: Europe | ヨーロッパ
8  purpose: Entrance Exam | 受験
9  self_introduction: adfafasd
10  sns_1: dfasdfas
11  sns_2: adfafasf
12  sns_3: fdasfsadff
13  user_id: '2'
14  commit: Send
15  controller: users
16  action: details_create
17permitted: false

それにも関わらず、どうやらDetailsモデルへのsaveができていないようです。
この「Detailsモデルへのsave」がなぜ期待通り行われないのかを教えていただきたいです。

程度の低い質問でしたら申し訳ございません。
また、回答に必要な情報に不足があれば、お手数ですがご指摘いただければ、随時追記いたします。

よろしくお願いいたします。

該当のソースコード

ruby
1[users_controller.rb]
2class UsersController < ApplicationController
3  
4  def show
5    @user = User.find(params[:id])
6  end
7  
8  def new
9    @user = User.new
10  end
11  
12  def create
13    @user = User.new(user_params)
14    if @user.save
15      log_in @user
16      flash[:success] = "Welcome to INTE! Your account has been creaeted."
17      redirect_to details_path
18    else
19      render 'new'
20    end
21  end
22  
23  def details
24    
25  end
26  
27  def details_create
28    @details = Detail.new(detail_params)
29    if @details.save  //ここが問題の箇所です。root_pathへのredirectが行われずdetailsにrenderされます。
30      redirect_to root_path
31    else
32      render 'details'
33    end
34  end
35  
36  
37  private
38  
39    def user_params
40      params.require(:user).permit(:name, :email, :image, :password, :password_confirmation)
41    end
42    
43    def detail_params
44      params.permit(:authenticity_token, :user_id, :mother_tongue, :japanese_level, :english_level,
45                                     :gender, :region, :purpose, :self_introduction, :sns_1, :sns_2, :sns_3)
46    end
47    
48end
49

html
1[details.html.erb]
2<% provide(:title, "user detail") %>
3
4<div class="user-detail-wrapper">
5  <div class="introduction">
6    <h3>①Authorize your account via sent Email.</h3>
7    <h3>②Let's register your user informations!<br>You can change it later.</h3>
8  </div>
9  
10  <div class="row user-detail-forms">
11    <div class="col-md-6 col-md-offset-3">
12      <%= form_with(model: @detail, local: true) do |f| %>
13        
14      
15        <%= f.label :mother_tongue, "Mother Tongue" %>
16        <%= f.select :mother_tongue, [["English", "English"], ["Japanese", "Japanese"], 
17        ["Other","other"]], include_blank: "Please select.", class:"form-control" %>
18        
19        <%= f.label :japanese_level, "Japanese Level" %>
20        <%= f.select :japanese_level, [["Beginner | 初心者", "Beginner | 初心者"], ["Capable of quite basic communication | 簡単な会話ならできる", "Capable of quite basic communication | 簡単な会話ならできる"], 
21        ["Capable of daily conversation | 日常会話ができる","Capable of daily conversation | 日常会話ができる"], ["Capable of advanced conversation | 難しい内容の会話ができる","Capable of advanced conversation | 難しい内容の会話ができる"], ["Almost native level | ネイティブとほとんど同レベル","Almost native level | ネイティブとほとんど同レベル"],
22        ["Native | ネイティブ","Native | ネイティブ"]], include_blank: "Please select.", class:"form-control" %>
23        
24        
25        <%= f.label :gender, "Gender(optional)" %>
26        <%= f.select :gender, [["he/him | 男性", "he/him | 男性"], ["she/her | 女性", "she/her | 女性"], 
27        ["they/them | その他","they/them | その他"], ["I don't want to tell | 言いたくない","I don't want to tell | 言いたくない"]], include_blank: "Please select.", class:"form-control" %>
28        
29        <%= f.label :region, "Region" %>
30        <%= f.select :region, [["Asia | アジア", "Asia | アジア"], ["Europe ｜ヨーロッパ", "Europe | ヨーロッパ"], 
31        ["Africa | アフリカ","Africa | アフリカ"], ["North/Central America | 北/中央アメリカ","North/Central America | 北/中央アメリカ"], ["South America | 南アメリカ","South America | 南アメリカ"],
32        ["Oceania | オセアニア","Oceania | オセアニア"], ["Other | その他","Other | その他"]], include_blank: "Please select.", class:"form-control" %>
33        
34        <%= f.label :purpose, "Purpose of Learning" %>
35        <%= f.select :purpose, [["Business | 仕事", "Business | 仕事"], ["School Classes | 学校の授業", "School Classes | 学校の授業"], 
36        ["Entrance Exam | 受験","Entrance Exam | 受験"], ["Trip | 旅行","Trip | 旅行"], ["Want to talk with Foreingers | 外国の人と話したい","Want to talk with Foreingers | 外国の人と話したい"], 
37        ["Qualifying Exam | 資格試験","Qualifying Exam | 資格試験"], ["Hobby | 趣味","Hobby | 趣味"], ["Other | その他", "Other | その他"]], include_blank: "Please select.", class:"form-control" %>
38        
39        <%= f.label :self_introduction, "Self Introduction" %>
40        <%= f.text_area :self_introduction, class: 'form-control self-intro', placeholder: "It is recommended that you write in simple English." %>
41        
42        <%= f.label :sns_1, "URL of Your SNS 1 (optional)" %>
43        <%= f.text_field :sns_1, class: 'form-control' %>
44        
45        <%= f.label :sns_2, "URL of Your SNS 2 (optional)" %>
46        <%= f.text_field :sns_2, class: 'form-control' %>
47        
48        <%= f.label :sns_3, "URL of Your SNS 3 (optional)" %>
49        <%= f.text_field :sns_3, class: 'form-control' %>
50        
51        <%= f.text_field :user_id, type: "hidden", value: "#{current_user.id}" %>
52        
53
54        <%= f.submit "Send", class: "btn btn-primary create" %>
55      <% end %>
56    </div>
57  </div>
58</div>

ruby
1[routes.rb]
2Rails.application.routes.draw do
3  
4  get 'sessions/new'
5  root 'static_pages#language'
6  get '/home_jp', to:'static_pages#home_jp'
7  get '/home_en', to:'static_pages#home_en'
8  get '/signup', to:'users#new'
9  get '/details', to:'users#details'
10  post '/details', to:'users#details_create'
11  get '/login', to:'sessions#new'
12  post '/login', to:'sessions#create'
13  delete '/logout', to:'sessions#destroy'
14  # For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html
15  resources :users
16end
17

ruby
1[detail.rb]
2class Detail < ApplicationRecord
3  belongs_to :user
4  validates :mother_tongue, presence: true
5  validates :japanese_level, presence: true
6  validates :english_level, presence: true
7  validates :region, presence: true
8  validates :purpose, presence: true
9  validates :self_introduction, presence: true, length: {maximum:300}
10end
11