Codeigniter Несколько вложений не работает, когда я выбираю вложения один за другим

Question

Я использую эту библиотеку для мультизагрузки https://github.com/stvnthomas/CodeIgniter-Multi-Upload

Проблема: Мой код работает нормально, когда я выбираю все вложения по одному, но всякий раз, когда я выбираю несколько вложений по одномуодин он загружает только последний, игнорируя другие файлы.

вот мой код:

HTML

<div class="card-body">
      <?php $attributes = array('name' => 'send_mail_today_interviews', 'id' => 'xin-form', 'autocomplete' => 'off');?>
      <?php $hidden = array('user_id' => $session['user_id']);?>
      <?php echo form_open_multipart('admin/send_mail/send_mail_today_interviews', $attributes, $hidden);?>
      <div class="row">
        <div class="col-md-6">
          <div class="form-group">
            <label for="from_email">From </label>
            <input type="text"   class="form-control" name="from_email" value="<?php echo $session["email"] ?>">
          </div>
        </div>

        <!-- <div class="col-md-6">
          <div class="form-group">
            <label for="to_email">To (Separate multiple emails by comma)</label>
            <input type="text"  class="form-control"   value="kamal@i2k2.com" name="to_email">
          </div>
        </div> -->

        <div class="col-md-4">
          <div class="form-group">
            <label for="to_email">To </label>
            <select multiple class="form-control" name="to_email[]" data-plugin="select_hrm" data-placeholder="<?php echo $this->lang->line('dashboard_employees');?>">
              <option value=""></option>
              <?php foreach($all_employees as $employee) {?>
                <option value="<?php echo $employee->email;?>" <?php if($employee->email=="kamal@i2k2.com"):?> selected="selected"<?php endif;?> ><?php echo $employee->first_name. ' ' .$employee->last_name;?></option>
              <?php } ?>
            </select>
          </div>
        </div>
      </div>
      <div class="row">
        <div class="col-md-6">
          <div class="form-group">
            <label for="subject">Subject</label>
            <input type="text"   class="form-control" name="subject" value="Interview Schedule Today || <?php echo $this->Xin_model->set_date_format(date("Y-m-d")) ?>">
          </div>
        </div>

        <div class="col-md-6">
          <div class="form-group">
            <label for="resume">Attachment</label>
            <span class="btn btn-primary btn-file"> <?php echo $this->lang->line('xin_browse');?>
            <input type="file" name="attachment" multiple="" id="attachment">
          </span>
          <?php if($system_setting[0]->job_application_format!=''){?>
            <br>
            <small>Allowed Files: <?php echo $system_setting[0]->job_application_format;?></small>
          <?php } ?>
          <br>
          <span id="sel_files"></span>
        </div>
      </div>

    </div>

    <div class="row">
      <div class="col-md-12">
        <div class="form-group">
          <label for="description">Message</label>
          <textarea class="form-control textarea" placeholder="Message" name="message" cols="30" rows="15" id="message"><?php echo $message ?></textarea>
        </div>
      </div>
    </div>

    <div class="form-actions">
      <button type="submit" class="btn btn-primary"> <i class="fa fa-check-square-o"></i> Send </button>
    </div>
    <?php echo form_close(); ?> 
  </div>

Код для загрузки файла

if(!empty($_FILES['attachments']['name'])){


            //Upload file

            $config['upload_path']          = './uploads/attachments/';
            $config['allowed_types']        = 'gif|jpg|png|JPG|jpeg|pdf|doc|docx|xlsx|csv|txt';
            $this->load->library('upload', $config);


            // Multi upload

            if (!$this->upload->do_multi_upload('attachments')){
                $Return['error'] = $this->upload->display_errors();
            }

            // if ( ! $this->upload->do_upload('attachments'))
            // {
            //  $Return['error'] = $this->upload->display_errors();
            // }

        }

        if($Return['error']!=''){
            $this->output($Return);
            exit;
        }