Unable to Preview PDFs using new Box.ContentExplorer

I've instantiated "new Box.ContentExplorer" and it loads fine. I am able to preview jpg/png, but am unable to preview PDFs. The version I am using is 1.35.1 (cli) and 4.4.0 within the "options". 

I've set "canPreview" to true, the files preview within box.com, but not within the Content Explorer. Can someone assist? Is there a setting I am missing? 

Thank you