When inserting a link in the body of an email that ReportWORQ will send, the URL line expects what’s entered to be a web address (eg, SharePoint, Google Drive, etc). In order to get it to recognize a network location (ie, file on a server), the URL must be preceded by file:///. So for me, the UNC syntax is
file:///\\servername\path\file_name.xlsx
A checkbox between the URL line and the Text to display line would be a good addition to automatically add the needed file:///. Another option would be to detect it like it currently does for email addresses by adding the mailto: prefix to it.