Popover: Does not update parent view on shown event

[Nosfistis]

Bug description:

This is a regression bug of 8.0.0 release.

I have a subject that fires on each shown/hidden event, and is merged to an observable to update a count:

  count$: Observable<number> = merge(
    interval(3000),
    this.isShownSubject.pipe(mapTo(0))
  );

However, the view does not update on shown. Even though the event is fired, and the observable emits, the entire containing view does not update at all. The hidden event works as intended.

I have checked the current code and realized that the NgbPopover.close() marks for change detection after the hidden event is fired, but the NgbPopover.open() does not. Code:

ng-bootstrap/src/popover/popover.ts

Line 258 in 1f466ed

transition$.subscribe(() => this.shown.emit());

ng-bootstrap/src/popover/popover.ts

Lines 267 to 276 in 1f466ed

	close() {
	if (this._windowRef) {
	this._renderer.removeAttribute(this._elementRef.nativeElement, 'aria-describedby');
	this._popupService.close(this.animation).subscribe(() => {
	this._windowRef = null;
	this.hidden.emit();
	this._changeDetector.markForCheck();
	});
	}
	}

I have manually tried adding the this._changeDetector.markForCheck(), but the view still does not update. Only explicitly adding this._changeDetector.detectChanges() fixes the issue.

It is even stranger that not only the directive content, but also the entire parent component view does not update (in the StackBlitz, the description bottom text does not change either). This occurs in OnPush and Default change detection strategies, even with animations disabled.

Link to minimally-working StackBlitz that reproduces the issue:

https://stackblitz.com/edit/angular-vsfpjy

Versions of Angular, ng-bootstrap and Bootstrap:

Angular: 10.2.3

ng-bootstrap: 8.0.0

Bootstrap: 4.5.3