title: Magento 2 shipping address custom dropdown field value not posting
body: <p>We have added custom field under shipping address in checkout page.</p>
  
  <p>It's select field and we are showing custom option from database.  It's working fine but when we click next and move to payment option to place an order at that time value not posting.  selected dropdown value not showing in console.</p>
  
  <p>If we add text field instead then it shows value posted in console.  What could be the issue?</p>
  
  <pre><code>     $jsLayout['components']['checkout']['children']['steps']['children']['shipping-step']['children']
      ['shippingAddress']['children']['shipping-address-fieldset']['children']['custom-field'] = [
                  'component' =&gt; 'Magento_Ui/js/form/element/abstract',
                  'config' =&gt; [
                      'customScope' =&gt; 'shippingAddress.custom_attributes',
                      'template' =&gt; 'ui/form/field',
                      'elementTmpl' =&gt; 'ui/form/element/select',                       
                      'id' =&gt; 'custom-field',
                        'options' =&gt; $optionarray
                  ],
                  'dataScope' =&gt; 'shippingAddress.custom_attributes.custom_field',
                  'label' =&gt; 'Custom Field',
                  'provider' =&gt; 'checkoutProvider',
                  'visible' =&gt; true,
                  'validation' =&gt; [],
                  'sortOrder' =&gt; 250,
                  'id' =&gt; 'custom-field'
  
              ];
  
  
  
  
  
      return $jsLayout;
  </code></pre>
  
  <p>Any help would be appreciated.</p>