How do I allow spaces to be input in Bootstrap Select?

May be something else is preventing you from entering space, bootstrap-select does no prevent your from entering spaces, checkout demo below:

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<link href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.11.0/css/bootstrap-select.min.css" rel="stylesheet"/>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.11.0/js/bootstrap-select.min.js"></script>


<select class="selectpicker" data-live-search="true">
  <option>Hot Dog, Fries and a Soda</option>
  <option>Burger, Shake and a Smile</option>
  <option>Sugar, Spice and all things nice</option>
</select>