Hi,
I created sample Angular 6 project and display scheduler in the sample site. Everything is looks good but if i place </router-outlet> outside my html it’s working fine where as if i placed in side header it’s not displaying.
I used below html template.
Unfortunately I don’t understand what goes wrong in your app and how I can help you based on your description.
Not sure that the work of </router-outlet> depends on Scheduler. https://angular.io/api/router/RouterOutlet
I can only advice you to redirect the question to the Angular forum (or smth like that).