Angular 10 behavior subject returns null after calling .next(value) method

Solution 1:

Are your services provided in root? If not, you may be getting multiple instances.

@Injectable({
  providedIn: 'root'
})
export class AuthenticationService {
...

Solution 2:

It seems like the auth service takes some time to fetch data, and by then the route is already rejected as it got null.

You can try adding some wait before approving/rejecting a route