title: Default option in <select> not showing
body: <p>I am experiencing a stupid issue with a <code>&lt;select&gt;</code>. My toolchain of choice is Vue.js with Bootstrap and I am trying to create a dynamic <code>&lt;select&gt;</code> that is populated with Vue. My issue however is that the default option in the <code>&lt;select&gt;</code> is not showing, instead the form-element is blank.</p>
  <p>This is my coding, the input group is almost identical to the example provided in the Bootstrap documentation. I also tried the suggestions mentioned in <a href="https://stackoverflow.com/questions/52860383/default-option-of-select-is-not-showing">this question</a> however they did not work.</p>
  <pre class="lang-html prettyprint-override"><code>&lt;div class=&quot;input-group mb-3&quot;&gt;
    &lt;div class=&quot;input-group-prepend&quot;&gt;
      &lt;label
          class=&quot;input-group-text&quot;
          for=&quot;action_manufacturer_input&quot;&gt;Manufacturer&lt;/label&gt;
    &lt;/div&gt;
    &lt;select
        v-model=&quot;form.manufacturer&quot;
        class=&quot;custom-select&quot;
        id=&quot;manufacturer_input&quot;&gt;
      &lt;option disabled selected value=&quot;undefined&quot;&gt;Please select one...&lt;/option&gt;
      &lt;option
          v-for=&quot;manufacturer in manufacturers&quot;
          v-bind:value=&quot;manufacturer.id&quot;&gt;
        {{ manufacturer.display_name }} : {{ manufacturer.full_name }}
      &lt;/option&gt;
      &lt;option v-on:click=&quot;toggle_input()&quot;&gt;Add new manufacturer...&lt;/option&gt;
    &lt;/select&gt;
  &lt;/div&gt;
  </code></pre>
  <p>As a sanity check I removed the Bootstrap styling however that did not change anything. My question: how do I get the default selected option to show?</p>
  <p>P.S. For what it's worth my back-end is Laravel, however I don't see how it could cause an issue.</p>