Upload files programmatically to users in wordpress

i'm using pods plugin to add new custom fields to user so i added 4 files custom fields and then trying to upload files to this fields from registration page and create new user but when i upload the files it did not generate all the images sizes and when open the new user from the admin panel the image not showing but the name is and the image post is created please any help

my code

 $uploadfiles = upload_files();

                $metas = array(
                    'uploadfiles1' => $uploadfiles[0]['attach_id'],
                    'uploadfiles2' => $uploadfiles[1]['attach_id'],
                    'uploadfiles3' => $uploadfiles[2]['attach_id'],
                    'uploadfiles4' => $uploadfiles[3]['attach_id'],

                );

                foreach ($metas as $key => $value) {
                    update_user_meta($user_id, $key, $value);
                }

upload_files function:

function upload_files()

{ $files_uploaded = array(); $files = $_FILES; $files_extensions = ["image/png", "image/jpeg", "image/bmp", "image/jpg", "application/pdf"];

$is_files_checked = check_upload_files($files, $files_extensions, 5);

if ($is_files_checked) {

    foreach ($files as $key => $file) {

        $file_name = get_file_name($key);
        $upload_file_name = ($_POST['registration_fname'] . '_' . (!empty($_POST['registration_mname']) ? $_POST['registration_mname'] . '_' : '') . $_POST['registration_lname'] . '_' . $file_name . '_' . time() . get_file_extension($file['type']));
        $upload_dir = wp_upload_dir();

        if (move_uploaded_file($file["tmp_name"], $upload_dir['path'] . "/" . $upload_file_name)) {
            //registration_FrontDriverLicense || registration_BackDriverLicense
            //registration_FrontEmirateID || registration_BackEmirateID
            //Passport || Visa_Stamp
            $uploaded_file['file_name'] = $file_name;
            $uploaded_file['upload_url'] = $upload_dir['url'] . "/" . $upload_file_name;

            $attachment = array(
                'guid'           => $uploaded_file['upload_url'],
                'post_mime_type' => $file['type'],
                'post_title'     => $upload_file_name,
                'post_content'   => '',
                'post_status'    => 'inherit'
            );

            $uploaded_file['attach_id'] = wp_insert_attachment( $attachment , $upload_dir['path']);
            require_once( ABSPATH . 'wp-admin/includes/image.php' );

             //Generate the metadata for the attachment, and update the database record.
            $attach_data = wp_generate_attachment_metadata( $uploaded_file['attach_id'] , $upload_dir['path']);
            wp_update_attachment_metadata( $uploaded_file['attach_id'], $attach_data);

            $files_uploaded[] = $uploaded_file;
        }
    }
    return $files_uploaded;
} else {
    //$is_files_checked files error....
    return $is_files_checked;
}

}

via Chebli Mohamed