Set Select2 selected values with JSON string

I have a select2 that's used to add multiple employees to a work permit. Adding the employees works with no issues but when the permit is viewed I need the added employees to be pre-selected on the select2. I can retrieve the values from the DB via ajax using a JSON string but the select2 only shows each value one at a time rather than as a multi select. Multiple is set to true when the select2 is generated.

My HTML page code is below

<legend><h5 class="text-semibold">Employees</h5></legend>
<div class="row">
    <div class="col-md-8 col-md-offset-2">
        <div id="select_employee_div" class="content-group-lg">
            <label class="control-label text-bold">Select Employees *</label>
            <select id="select_employee" class="form-control multi-select-search">

            </select>
        </div>
    </div>
</div>

My select2 initialisation code is below

// Select with search
$('.multi-select-search').select2({
    multiple: true
});

My ajax code is below.

$.ajax({
    type: "POST",
    url: 'php_files/permit_php_files/permit_employee_process.php',
    dataType: 'JSON',
    data: {
        permit_id: $('#permit_id').val()
    },
    success: function(data) {

    var my_obj = data;
    $.each(my_obj, function (i, z) {

            $("#select_employee").val(my_obj[i].employee_id).trigger('change');
        });
   }
});

My PHP Code is below

$stmt = $mysqli->prepare("SELECT employee_id FROM tbl_permit_employee WHERE permit_id = ?");
$stmt->bind_param("i", $permit_id);
$stmt->execute();
$stmt->store_result();
$stmt->bind_result($employee_id);
$row_array = array();

while($stmt->fetch()) {
    $tmp = array();
    $tmp['employee_id'] = $employee_id;
    array_push($row_array, $tmp);
}
$stmt->close();

echo json_encode($row_array);

The problem is in success handler of ajax request: you have to pass an array to Select2 val() function (see https://select2.org/programmatic-control/add-select-clear-items#selecting-options), like in the code below:

var arr = [];
for (var i in data) {
    arr.push(data[i].employee_id);
}
$("#select_employee").val(arr).trigger('change');

Here is a working jsfiddle: https://jsfiddle.net/beaver71/h92jmy2w/

P.S.: ajax is simulated via echo feature