How to project one observable to another?

I resurrected the wombats from that other post and used this in HomePage:

wombats: Observable<string[]>;

constructor(private _wombats: WombatService) {
}

ngOnInit(): void {
  this.wombats = this._wombats.wombats();
}

<div>{{wombats | async}}</div>

After some time passes, I see “4 wombats, 16 wombats, 36 wombats, 64 wombats”. I wonder what could be different from your situation. Could it possibly be an rxjs version issue? I’m still using ionic 3 / rxjs 5, fwiw.