I had this problem once (long ago).
You need to understand that ALL of your user (aside anonymous) are part of the register group. In your case I would use 4 groups; Anon, Registered, Non-suscribers and Subscribers.
Then you will have less troubles to compartiment.
Also with time I stopped to use the group homepage option (that require different pages) to use the plugin group (same page different content).
Hope this helps to solve your case