Bootstrap 4 navbar-toggler-icon does not appear

Update:

navbar-inverse is no longer available in B4 version, you can use navbar-dark instead.

Use navbar-inverse bg-inverse instead of .navbar-default

<section role="navigation">
  <nav class="navbar navbar-inverse bg-inverse navbar-toggleable-sm fixed-top"><!-- navbar-inverse -->

    <div class="container">

      <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#myNavigation" aria-controls="myNavigation" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
      </button>

      <a href="#" class="navbar-brand">KP</a>

      <div class="collapse navbar-collapse" id="myNavigation">
          <div class="navbar-nav">
            <a class="p-3 nav-item nav-link active " href="#">Home</a>
            <a class="p-3 nav-item nav-link " href="#">About</a>
            <a class="p-3 nav-item nav-link " href="#">Contact Me</a>
          </div><!-- <div class="navbar-nav"> -->
      </div><!-- <div class="collapse navbar-collapse"> -->

    </div><!-- <div class="container"> -->

  </nav>
</section>

Updated fiddle