Angular Material: <mat-option> doesn't work with async data

Question

I've quickly refactored an existing example from the Angular Material site (please see https://stackblitz.com/edit/angular-7povmz?file=app%2Fselect-optgroup-example.ts) to asynchrnously load data using setTimeout(). However, the select drop down doesn't load the pokemons, why?

Here's the original working example that loads the select drop down synchronously https://stackblitz.com/angular/jbgpoqrmveb?file=app%2Fselect-optgroup-example.ts

Answer 1

Nevermind.. my fundamental understanding of Angular is somewhat lacking. I have to use the combination async pipe and Observable/Promise to make this work.