workspdx on "[Plugin: W3 Total Cache] Can't upload files to CDN (500 error)"

I'm having difficulty when uploading files to my CDN. The issue presents regardless of CDN provider (I've tried both Amazon Cloudfront & Rackspace Cloud Files). I encounter a 500 error after waiting 45s for the upload to process. The uploader states 'timeout' then retries. I'm running the latest version of W3TC.

When running the uploader the Javascript console shows:

Failed to load resource: the server responded with a status of 500 (Internal Server Error) http://www.mydomain.com/wp-admin/admin.php?page=w3tc_cdn
POST http://www.mydomain.com/wp-admin/admin.php?page=w3tc_cdn 500 (Internal Server Error) jquery.js?ver=0.9.4:5
send jquery.js?ver=0.9.4:5
x.extend.ajax jquery.js?ver=0.9.4:5
W3tc_Popup_Cdn_Export_Library.process popup.js?ver=0.9.4:239
W3tc_Popup_Cdn_Export_Library.retry popup.js?ver=0.9.4:272
(anonymous function) popup.js?ver=0.9.4:268

Any thoughts? Thanks!

https://wordpress.org/plugins/w3-total-cache/