ドロップダウンメニューが開かない場合があります。

問題点

Bootstrapのnavでheaderにドロップダウンメニューを導入しているのですが、ドロップダウンが開く場合と開かない場合があり困っています。

navbarには現在ビューのあるリンクとしてHome画面とEdit画面（ドロップダウン内）へのリンクがあるのですが、それらのリンク先へ遷移した直後にドロップダウンメニューが動かなくなってしまいます。しかし、ブラウザで再読込（更新）するとドロップダウンメニューが動くようになります。

やったこと

jsの問題かと思い調べてみたのですが、なかなか適切な資料も見つからず解決には至っていません。

下記にコードを添付いたします。よろしくお願いいたします。

"routes.rb"

Ruby
1Rails.application.routes.draw do
2  root   'static_pages#home'
3  get    '/help' => 'static_pages#help'
4  get    '/about' => 'static_pages#about'
5  get    '/contact' => 'static_pages#contact'
6  get    '/signup' => 'users#new'
7  get    '/login' => 'sessions#new'
8  post   '/login' => 'sessions#create'
9  delete '/logout' => 'sessions#destroy'
10  resources :users
11  resources :account_activations, only: [:edit]
12  resources :password_resets,     only: [:new, :create, :edit, :update]
13end

"_header.html.erb"

HTML
1<nav class="navbar navbar-fixed-top navbar-expand-lg navbar-dark bg-primary">
2  <div class="container">
3    <a href="/" class="navbar-brand">
4      Body-Weight App
5    </a>
6    <ul class="navbar-nav">
7      <% if logged_in? %>
8        <li><a  href="/" class="nav-link">Home</a></li>
9        <li><a  href="#" class="nav-link">Help</a></li>
10
11<!--問題のドロップダウン部分です-->
12        <li  class="dropdown">
13          <a href="#" class="nav-link dropdown-toggle" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
14            Account<span  class="caret"></span>
15          </a>
16          <div class="dropdown-menu" aria-labelledby="navbarDropdown">
17             <a  href="/users/19/edit" class="dropdown-item">Settings</a>
18             <div class="dropdown-divider"></div>
19             <a  href="/logout" class="dropdown-item" rel="nofollow" data-method="delete">Log Out</a>
20          </div>
21        </li>
22<!--以上-->
23      <% else %>
24        <li><a  href="#" class="nav-link">Help</a></li>
25      <% end %>
26    </ul>
27  </div>
28</nav>

"custom.scss"

Sass
1@import "bootstrap";
2
3$main-blue:#428bca;
4$light-gray:#777777;
5
6li{
7  list-style: none;
8}
9
10
11.dropdown-item{
12  color:$main-blue;
13}
14
15
16.footer{
17  margin-top: 100px;
18  border-top: 1px solid $main-blue;
19  small{
20    float:left;
21    color:$main-blue;
22  }
23  ul{
24    float:right;
25  }
26  li{
27    float:left;
28    margin-left: 15px;
29  }
30  a{
31    color:$main-blue;
32  }
33}

"application.js"

Javascript
1// This is a manifest file that'll be compiled into application.js, which will include all the files
2// listed below.
3//
4// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, or any plugin's
5// vendor/assets/javascripts directory can be referenced here using a relative path.
6//
7// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
8// compiled file. JavaScript code in this file should be added after the last require_* statement.
9//
10// Read Sprockets README (https://github.com/rails/sprockets#sprockets-directives) for details
11// about supported directives.
12//
13//= require rails-ujs
14//= require activestorage
15//= require turbolinks
16//= require_tree .
17//= require bootstrap
18//= require bootstrap-sprockets

"_head.htnl.erb"

HTML
1<head>
2  <title><%= full_title(yield(:title)) %></title>
3  <%= csrf_meta_tags %>
4  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous">
5  <%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
6  <%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %>
7</head>

"application.html.erb"

HTML
1<!DOCTYPE html>
2<html>
3    <%= render "layouts/head"%>
4  <body>
5    <%= render "layouts/header" %>
6    <div class="container">
7      <%= render "layouts/flash" %>
8      <%= yield %>
9      <%= render 'layouts/footer' %>
10    </div>
11    <script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
12    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
13    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
14  </body>
15</html>