Sites added to this zone must use the prefix https

Issue:When trying to add a https website to a Internet Security Zone, the error "Sites added to this zone must use the prefix https:" appears.
Environment:
Internet Explorer on Windows
Symptoms:
Typically, this happens when the website does not have a https prefix, however, sometimes this error can occur when the website being added does have an https prefix!
Solution:
This was occurring on a system with a seemingly unrelated setting.
Using administrative rights:
Computer Policy > Computer Configuration > Administrative Templates > Windows Components > Internet Explorer
Find the setting "Security Zones: Use only machine settings"
If this is Disabled or Not Configured, try changing this to Enabled.
Close the Internet Explorer browser.
Run "gpupdate /force"
Restart Internet Explorer and try again.