How to handle the Angular material dropdown when got stuck on selection?

Question

I have one dropdown, when selecting one dropdown we have some funtionality. But, the selected option remains there and I am not able to select other dropdown.

So, I used this solution for the problem.

// reset dropdown value
this.subscriptions.add(this.ngZone.onStable.subscribe({next: () => this.selectedAction = -1}));

I am not able figure out why this is happening.