How to fix the header in the HTML5 context menu

test - internet explorer 11 html5 video not working

I have been working on an intranet website for over 6 months where I used the HTML and HTML5 meta tag to force Internet Explorer not to emulate an older version of the browser and that worked fine.

The reason I did this is because the place I work at uses a policy setting to enable Compatibility View for all intranet sites. This approach using the setting worked in Internet Explorer 9.

More than a month ago I was upgraded to Internet Explorer 11 and the website was still working as expected.

Today this no longer works as expected, I can't say for sure, but I think the policy that enforces the compatibility view wasn't enabled in IE11 and now it is ... and since that was enabled the compatibility metatag is no longer do what is expected and this site is running in enterprise mode emulating IE8.

Does anyone know how to fix this and force IE11 to be used on an intranet website when "enterprise mode" compatibility is enforced? and can not be deactivated via the browser settings?

TO EDIT

I just tried adding a custom header in my web.config as explained in this answer https://stackoverflow.com/a/18257208/98706

and that didn't work for me I'm still getting the following message in the developer toolbar console from

It's like version 8 is treated as having this intranet compatibility setting enabled in IE11.

This post: https://www.leapinggorilla.com/Blog/Read/1016/ie-ate-my-css---disabling-compatability-mode explains that well, I haven't tried this header via code and ours Users have no way of changing their browser settings. None of the other changes have worked so far.

TO UPDATE

Please read my comment on this post about what the difference between Enterprise Mode and Compatibility Mode is because it matters.