Geocortex Essentials IFRAME Bug

I've embedded a site in an IFRAME, however, the measurement tool does not work properly when viewing from the Iframe URL. I've searched and it seems there were similar bugs in version 3+. I am using version 4.1.0 and HTML viewer 2.2

The tool does not report the distances and at the end I just get a blank black box.

Is there a known bug?