Library not loading in Google App Engine

I am migrating my CI app to Google App Engine and I'm having issues with a 3rd party library not loading, and no error messages are present.

The library is from Go Cardless, and sits in the "third_party" folder.

It is loaded as shown below (this method works on a typical WAMP setup):

PHP Code:

$this->load->add_package_path(APPPATH.'third_party/GoCardless/');
$this->load->library('GoCardless'); 


But on GAE, I get a blank page, with no errors in the log.

If I comment out the 2nd line, where the library is loaded, the page will load fine.

Again, this approach worked flawlessly on a local WAMP setup and a remote VPS server.