//replace it with your script
<script>
$('#mySelect2').select2({
dropdownParent: $('#myModal')
});
</script>
<div id="myModal" class="modal fade" tabindex="-1" role="dialog" aria-hidden="true">
...
<select id="mySelect2">
...
</select>
...
</div>
...
<script>
$('#mySelect2').select2({
dropdownParent: $('#myModal')
});
</script>
data-control="select2" data-placeholder="Select payment method" data-dropdown-parent=“#modal”