Files not being removed from Google Cloud Storage

I am successfully using the Google Cloud Storage Module to upload files via Drupal to the bucket within my Google cloud project. This works for a field or an uploaded file.

My issue arises when I come to delete the file(s) from Drupal. It is removed from the Drupal site but not from the Google bucket. However, I can delete the file from within my Google Cloud Project screen.

I have tried recreating the Google service account to see if that had any impact - it didn't. I have also tried explicitly defining the service account as an owner of the bucket - again no luck. I have cleared the Drupal cache - nothing. I have also waited overnight in case there were any propagation issues between the Drupal delete and the removal from the Cloud - again nothing, the file is still in the bucket.

I have Libraries 7.x-2.1 installed. I have also applied this work around (https://drupal.org/node/1852388) to get the latest Google API for PHP to load. I am also hosting the website on a Pantheon account.

I'm hoping somebody might be able to point me in the right direction. Any advice would be greatly appreciated.