Saving images from Gravity Forms repeatable File Upload as post attachments

I am trying to upload multiple images as attachments to a post using Gravity Forms and the Gravity Forms + Custom Post Types plugin.

I have a repeatable File Upload field using the Gravity Forms gform_column_input_filter. See this question for how it was achieved.

I then adapted this code from BandonRandon to use the repeatable File Upload field as below:

 add_filter("gform_after_submission", "nifty_add_post_attachements", 10, 3);
 function nifty_add_post_attachements($entry) {

 //you'll need this later, TRUST ME.
 if ( !function_exists('wp_generate_attachment_metadata') ) {
    require_once(ABSPATH . 'wp-admin/includes/image.php');
 }

//do we even have a file?
 if ( isset($_FILES['input_2']) ) {
     $file_urls = $entry['2']; //great but what is its url?
     $file_array = unserialize($file_urls);

     foreach ( $file_array as $file_url ) {

         $upload_dir = wp_upload_dir(); //where do you want to put it?
         $file_data = file_get_contents($file_url); //show me what you're made of
         $filename = basename($file_url); //so cute but what's its name?
         if(wp_mkdir_p($upload_dir['path'])) //can we put it there?
         $file = $upload_dir['path'] . '/' . $filename; //yes great
         else //or no, okay fine let's try somewhere else
         $file = $upload_dir['basedir'] . '/' . $filename; //get the whole location
         file_put_contents($file, $file_data); // tada home at last

        $wp_filetype = wp_check_filetype($filename, array('jpeg' => 'image/jpeg','jpg' => 'image/jpeg', 'gif' => 'image/gif', 'png' => 'image/png') ); //is it the right type of of file?
         $attachment = array( //set up the attachment
         'post_mime_type' => $wp_filetype['type'],
         'post_title' => sanitize_file_name($filename),
         'post_content' => '',
         'post_status' => 'inherit'
         );

        $attach_id = wp_insert_attachment( $attachment, $file, $entry['post_id'] ); //insert attachment
        $attach_data = wp_generate_attachment_metadata( $attach_id, $file ); //asign the meta
        wp_update_attachment_metadata( $attach_id, $attach_data ); //update the post
    }
    //remove the entry
     //(to keep the entry comment or delete these line)
     // IMPORTANT See:  http://pastebin.com/quvsvGHJ for the function
     /*if(!function_exists('sedc_gform_remove_entries')){ die('next time maybe you should read the comments');}
     else{ nifty_gform_remove_entries($entry, $form );}*/
 }
}

I have tried dumping the $_FILES[‘input_2’] using the following code at the top of the nifty_add_post_attachements function but no output appears on my screen, the post is still created, and the form ajax loading spinner just hangs.

<pre>
    <?php print_r($_FILES['input_2']); die();?>
</pre>

Any help or pointers in the right direction would be appreciated.