NavigationStart Event is not Firing/Triggering on refresh

Question

I have a component that has router events like NavigationStart & NavigationEnd. While they work perfectly on visiting a new route but I am facing an issue with NavigationStart event which does not fire on refresh but NavigationEnd event do fire. Below is the code snippet. Is this a intended behavior?

navgState: NavigationStart;

constructor(private router: Router,
    private activatedRoute: ActivatedRoute) {

    this.router.events.subscribe((event) => {
      if (event instanceof NavigationStart) {
        console.log("Inside of NavgStart");

        this.navState = {
        id: value.id,
        navigationTrigger: value.navigationTrigger,
        restoredState: value.restoredState,
        url: value.url
      };

      }
    });

    this.router.events.pipe(filter(value => value instanceof NavigationEnd)).subscribe((value: any) => {
      this.someMethod(value);
    });
  }