get all the data from ng-select's observable items

Question

I am planning to add select all for the ngSelect where my ng-select is similar to this

<ng-select formControlName="filterValue" [items]="filterValues | async"
    [typeahead]="filterValuesInput"
    [multiple]="true"
    (open)="getFilterValues(pref.id)"
    [loading]="filterValuesLoading"
    bindLabel="name"
    bindValue="id">
</ng-select>

I am calling the backend to get the relevant data as per the user's input using typeahed. I am calling selectAll by putting button in ng-select's header

<ng-template ng-header-tmp>
<button (click)="selectAll('filterValue', filterValues)">Select all</button> 
 </ng-template>

my selectAll method is like this

selectAll(formParam: string, list: any) {
    if(formParam === 'filterValue') {
      let orgs:Organization[] = []; 
      list.subscribe(org =>{
        orgs =[...org] 
      })
      this.myForm.get(formParam).setValue(orgs.map(option => option.id));
    } 
    else {
      this.myForm.get(formParam).setValue(list.map(option => option.id));
    }
  }

I am getting 'orgs null even though I can see data on ng-select list in UI.