Internet Explorer Mode Flip-Flops Between On and Off

GreatToHearFromYou 

Not sure if this will help anyone, but one of the other things I discovered after much frustration was that if you add an enterprise site list or make any changes to it, Edge will take approximately 1-1.5 minutes to load the new list the next time it starts up. 

You'll see an EmieSitelist.xml file pop into %localappdata%\Microsoft\Edge[version]\User Data when it's loaded. Prepopulating this file unfortunately does not change this behavior. 

To clarify as well, I noticed that even if I specify a sites list in Edge at HKLM\SOFTWARE\Policies\Microsoft\Edge, IE mode will not work properly unless the Enterprise Mode Sites List is configured for Internet Explorer at HKLM\SOFTWARE\Policies\Microsoft\Internet Explorer\Main\EnterpriseMode). 

Interestingly, if you configure the sites list in Edge and then remove the list from your IE Enterprise Mode key or delete the key entirely, it will continue to work on that machine. It just won't work if you start with just the Edge key on a new machine. 

Haven't tried this in group policy yet but I expect it would work the same.