Embedded Browser object doesn't draw some web sites

I have a home automation application (Charmed Quark) that uses a COM object of type CLSID_WebBrowser to open a web page.  I have used the FEATURE_BROWSER_EMULATION registry entry to force IE11 and my user agent is Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko which matches the user agent for my stand-alone IExplorer.

However, some web-sites work fine in the stand alone brower, but not in the embedded brower.  Why?

https://www.google.com/maps/preview/?force=webgl

generates a security related script error then refuses to draw anything in the main window.  The "classic" version of google maps works fine in embedded and stand-alone browser.

https://www.icloud.com/#find

generates an unsupported browser error and then runs normally

https://www.anylistapp.com/web

doesn't draw anything in the main window.

I've looked through all the feature control registry entries but none seem likely to help solve this problem.  Thanks for any ideas!  --Bob