Select2 - Item not rendered after Ajax Selection

I setup a Select2 Object to work wit han ajax source data. This is the Html

<select class="form-control" id="customerSelect" style="width: 200px !important;"></select>

This is the JS to initialize and fill the select

$("#customerSelect").select2({
  dropdownAutoWidth: true,
  templateResult: iconUser,
  minimumInputLength: 3,
  placeholder: "-- Select a customer --",
  ajax: {
    url : "/admin/ajax/orders.php",
    type:'POST',
    dataType: 'json',
    delay: 250,
    data: function (params) {
      return {
        searchTerm: params.term,
        action: 'listCustomers',
        isJs: true
      };
    },
    processResults: function (result) {
      return {
        results: $.map(result['data'], function (item) {
          return {
            id: item.id,
            customerName: item.customerName,
            stockName: item.stockName,
            customerType: item.customerType
          }
        })
      };
    }
  }
});

And this is my template function, I add an icon in front of the text

function iconUser (userDetails) {
  return $("<span><i class=\"fa-solid fa-"+userDetails.customerType+"\"></i> "+userDetails.customerName+" - "+userDetails.stockName+"</span>");
}

Everything works fine before the loading, the select shows up with the right placeholder When I click on it, it load correctly the search results but once I click on an item, any, it doesn’t appear anything on the select

Here’s the html code after I click on the select, it seems the rendered space is empty, even if the right element is populated (user_748)

<select class="form-control select2-hidden-accessible" id="customerSelect" style="width: 200px !important;" data-select2-id="select2-data-customerSelect" tabindex="-1" aria-hidden="true">
  <option value="user_748" data-select2-id="select2-data-116-dhe1"></option>
</select>

<span class="select2 select2-container select2-container--default select2-container--below" dir="ltr" data-select2-id="select2-data-1-39br" style="width: 200px;">
  <span class="selection">
    <span class="select2-selection select2-selection--single" role="combobox" aria-haspopup="true" aria-expanded="false" tabindex="0" aria-disabled="false" aria-labelledby="select2-customerSelect-container" aria-controls="select2-customerSelect-container">
      <span class="select2-selection__rendered" id="select2-customerSelect-container" role="textbox" aria-readonly="true"></span>
      <span class="select2-selection__arrow" role="presentation">
        <b role="presentation"></b>
      </span>
    </span>
  </span>
  <span class="dropdown-wrapper" aria-hidden="true"></span>
</span>

I tried to search in the forum and in the web, but with no luck

You need to add a templateSelection to tell the value to display when selected.

templateSelection: function(data) {
   return data.customerName
},

var data = [{
    id: 1,
    customerName: 'Lebron',
    stockName: 'IBM',
    customerType: 'person'
  },
  {
    id: 2,
    customerName: 'Nicole',
    stockName: 'CIA',
    customerType: 'dog'
  }, {
    id: 3,
    customerName: 'Antuan',
    stockName: 'FR3',
    customerType: 'envelope'
  }
]

$("#customerSelect").select2({
  dropdownAutoWidth: true,
  templateResult: iconUser,
  templateSelection: function(data) {
    return data.customerName
  },
  minimumInputLength: 0,
  placeholder: "-- Select a customer --",
  data: data,
});


function iconUser(userDetails) {
  return $("<span><i class=\"fa-solid fa-" + userDetails.customerType + "\"></i> " + userDetails.customerName + " - " + userDetails.stockName + "</span>");
}

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.2/css/all.min.css" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<link href="https://cdn.jsdelivr.net/npm/select2@4.1.0-rc.0/dist/css/select2.min.css" rel="stylesheet" />
<script src="https://cdn.jsdelivr.net/npm/select2@4.1.0-rc.0/dist/js/select2.min.js"></script>

<select class="form-control" id="customerSelect" style="width: 200px !important;"></select>