[AC-5534] iOS Document Viewer does not open PDF files (iOS 11.2)

Document Viewer is not opening PDFs, instead it is showing a grey screen with the pdf filename. (see attached). The same result is usually seen when a pdf cannot be found. This is affecting live apps that were working fine when uploaded, but now PDFs will not open. My assumption here is that it is due to iOS 11.2 but I have no confirmation on that. The PDF opens correctly when viewing on a simulator, but not on device.

var win = Ti.UI.createWindow({
	backgroundColor: '#fff'
});
win.open();

var docViewer = Ti.UI.iOS.createDocumentViewer({
	url: 'sample.pdf'
});

docViewer.show();