I have no idea what is causing this. This just became a recent thing and it has happened on both Pacifica and Widow's Court. And only to Zone B. You can still capture the zone because it is still there, but it's just that the icon goes away. You can't really tell what state that zone is in while away from it after the glitch has happened. And I don't think there is any Smoke involved. I'm on Xbox One. If I need to share a clip of it happening, I have some that I can dig up if need be.