Q:

Dropup Bootstrap class always remain in active and show states

dropdown-item class works fine only when used dropdown class but not worked in dropup class. 
Dropup not works after clicks the all sub-menu item. Because all dropdown-item becomes active and show after every clicks.
Code Snippet and Scenario Images of problem given below.
1. First Image: All Submenu Active and Show 

2. Second Image: Inspect Element 

<!doctype html>
<html lang="en">
  <head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css">

    <title>DropUp bootstrap</title>
  </head>
  <body>
  
<ul class="nav flex-column">

    <li class="nav-item dropdown mb-5">
        <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#">DropDown</a>
        <div class="dropdown-menu">
            <a class="dropdown-item" data-toggle="tab" href="#hello1">Hello1</a>
            <a class="dropdown-item" data-toggle="tab" href="#hello2">Hello2</a>
            <a class="dropdown-item" data-toggle="tab" href="#hello3">Hello3</a>
        </div>
    </li>

    <li class="nav-item dropup mt-5">
        <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#">DropUp</a>
        <div class="dropdown-menu">
            <a class="dropdown-item" data-toggle="tab" href="#hello1">Hello1</a>
            <a class="dropdown-item" data-toggle="tab" href="#hello2">Hello2</a>
            <a class="dropdown-item" data-toggle="tab" href="#hello3">Hello3</a>
        </div>
    </li>

</ul> <!-- End nav -->

<div class="tab-content mt-1">

    <div class="tab-pane fade" id="hello1">
      <h1>Hello 1</h1>
    </div> <!-- End hello1 -->

    <div class="tab-pane fade" id="hello2">
      <h1>Hello 2</h1>
    </div> <!-- End hello2 -->

    <div class="tab-pane fade" id="hello3">
      <h1>Hello 3</h1>
    </div> <!-- End hello3 -->

</div> <!-- End tab-content -->


    <!-- Optional JavaScript -->
    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>
  </body>
</html>

A:

This is a known issue in Bootstrap 4.0.0: https://github.com/twbs/bootstrap/issues/25759
A workaround is to use both dropdown and dropup classes for the "dropdown" element.
https://www.codeply.com/go/YiXNLqAzwL
<li class="nav-item dropdown dropup mt-5">
        <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#">DropUp</a>
        <div class="dropdown-menu">
            <a class="dropdown-item" data-toggle="tab" href="#hello1">Hello1</a>
            <a class="dropdown-item" data-toggle="tab" href="#hello2">Hello2</a>
            <a class="dropdown-item" data-toggle="tab" href="#hello3">Hello3</a>
        </div>
</li>

