This is a simple code example I tested using bootstrap-select:
<html>
<head>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.13.1/css/bootstrap-select.min.css">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.13.1/js/bootstrap-select.min.js"></script>
</head>
<body>
<select class="selectpicker" data-live-search="true">
<option>Mustard</option>
<option>Ketchup</option>
<option>Relish</option>
</select>
</body>
</html>
You can see how the above code works by clicking on this link: https://jsfiddle.net/vpjnmatk/6/
When I click on the select box, the drop-down menu does not appear. It's confusing because I believe I have included all the necessary dependencies. Any thoughts on why this might be happening?