PDF space export shows over 100% progress, download link is never rendered

When rendering certain content, the PDF Exporter will get confused as to how much progress it has made, and will show over 100% progress as it converts the intermediate HTML into a PDF. As soon as progress goes past 100%, the long running task display stops refreshing, preventing it from ever showing the final completion/failure message.

Workaround

Browsing away from the page and using the browser's back button works in Firefox to trick the final task status to render.