I got a push reminder: "We haven't seen you on *** for months". Following the invitation to login (see screenshot) the login page of that collection is called, that was set for login and registry. After login I was not redirected to that collection I am registered. So normally the user may not know where she is and what's about. If she remembers the collection she had registered for and calls this collection she must login again, to access. (What has become of the login before?)
Another approach: If she tries to find out where she is registered for and tries to call the profile (See screenschot), than the same happens. She gets the response, that she is not logged in.
That may be very frustrating for users.
I don't think that this behavior is caused by using a subdomain for that collection, the user has been registered.
Hope there is a solution
Thanks and Regards, Will
Here are the screenshots: