CODEIGNITER: I can’t input/search any words and not showing the datavalue from my database using select2

Selection of Items/Search of items
I have problem inputting a words i can’t input or click in the search box or maybe i have error in my code or in my script.

My View:

<select type="text" name="protitle" class="form-control" id="recipient-name123" required>
     <option>Select Bus</option>
</select>

My script:

<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jqueryvalidate/1.19.3/jquery.validate.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.13/css/select2.min.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.13/js/select2.min.js"></script>


<script>
    $(document).ready(function() {
        $('#recipient-name123').select2({
            ajax: {
                url: '<?php echo base_url("projects/searchbus"); ?>',
                type: 'POST',
                dataType: 'json',
                delay: 250,
                data: function(params) {
                    return {
                        protitle: params.term
                    };
                },
                processResults: function(data) {
                    return {
                        results: $.map(data, function(item) {
                            return {
                                text: item.cat_name + " - " + item.cat_busnum,
                                id: item.cat_name + " - " + item.cat_busnum
                            };
                        })
                    };
                },
                cache: true
            },
            minimumInputLength: 1
        });
    });
</script>

This is my Model:

public function search_bus($protitle) {
        $this->db->like('cat_name', $protitle);
        $this->db->or_like('cat_busnum', $protitle);
        $query = $this->db->get('assets_category');
        return $query->result();
    }

This is my controller:

public function searchbus() 
{
  $protitle = $this->input->post('protitle');
  $data['results'] = $this->project_model->search_bus($protitle);
  $this->load->view('backend/All_Projects', $data);
}

I just want to search in the select/dropdown and show the data from my database. Do have any suggestion to remove, edit, or add to my code to work? Thank you!