<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
Thank you for reporting this problem to us. I managed to reproduce it on my side. Your request has been linked to the appropriate issues. You will be notified as soon as it is resolved.
As a temporary workaround, you can try removing optional hyphens from the document before converting it to PDF. Please see the following code example:
// Open document.
Document doc = new Document("in.docx");
// Remove optionalHypens from the document.
doc.Range.Replace(ControlChar.OptionalHyphenChar.ToString(), "", false, false);
// Save document to PDF.
Hope this helps.