Unity Mirror, multi additive level, Scene specific Canvas and UIs are showing on all scenes

I followed the Example level for the Unity Additive Level. When I use the components for the example everything works, but when I create my own the user interface components from all scenes show at the same time on the server/host. For example the UI Text over the Portal on subscene2 is also visible on subscene1 and vice a versa. Obviously I am missing something but I can't figure it out. There are many working parts which is why I am not showing anything yet. I am hoping this is a common mistake that someone with experience can just pinpoint.

Thanks for any help

 

Update, I was wrong. The UI on the example doesn't work either. I find this very strange that the UI on the example provided in the Mirror package doesn't work.

 

Did you ever figure it out? Currently having this issue as well.

 

Have exactly the same issue and cant figure out whats the point