I am trying to replace the current registration view with a view I am creating. So when I am viewing a class and click on Manage Registrations I get taken to the following page, node/%/registrations and I only see the people associated with that class.

I can create my new view, create a context filter based on Host entity ID and replace the current view. But if I leave the context filter on I don't see anyone, and if I take it off I see everyone who has ever sign up for a class.

I don't know how I can link the value in node/% to a value that I can filter on like Host entity ID while creating this new view.