A common issue encountered by many customers not just of J!WHMCS Integrator or Integrator 3 but also those customers that use a CDN to serve up their images and static assets is that of cross domain fonts not being rendered properly. This is directed at our customers using J!WHMCS or Integrator 3, but it may be useful to others as well.
How do you know if you are experiencing this issue?
For most, it's fiarly straight forward. If you view your Joomla or Wordpress site and you have a great looking font, or maybe some icons provided through the Font Awesome font library, but then you go to your WHMCS site and it looks like the fonts are standard Arial or Tahoma or the FontAwesome icons look like little boxes instead of their nice little icons, then you may have this issue. Using WHMCS with SSL but retrieving content that isn't using an SSL connection can also cause this issue, so you should check your URL to see if you are using SSL that you have the green box or lock in the browser bar.