Hello, I have below code of Mat-select with virtual-scroll.
I have get the value of mat-select in formBuilder but did not reflect the value which I select in the mat-item-select.

<mat-form-field appearance="outline">
<mat-select multiple (openedChange)="openChange($event)" formControlName="itemSelect">
<mat-select-trigger>
{{ itemTrigger }}
</mat-select-trigger>
<cdk-virtual-scroll-viewport itemSize="5" minBufferPx="200" maxBufferPx="400" class="example-viewport-select">
<mat-option *cdkVirtualFor="let list of skillSet" [value]="list.data" (onSelectionChange)="onSelectionChange($event)">
{{list.data}}
</mat-option>
</cdk-virtual-scroll-viewport>
</mat-select>
<mat-error *ngIf="!addCompany.controls['itemSelect'].valid && addCompany.controls['itemSelect'].touched">
{{ titleAlert }}
</mat-error>
</mat-form-field>

<mat-horizontal-stepper [linear]="true" [selectedIndex]="selectedIndex">
  <mat-step *ngFor="let step of steps; let i = index" [editable]="true" [optional]="false" [completed]="selectedIndex > i">

<mat-horizontal-stepper [linear]="true" [selectedIndex]="selectedIndex"

<mat-horizontal-stepper [linear]="true" [selectedIndex]="selectedIndex"

<mat-step *ngFor="let step of data.steps; let i = index; trackBy: getObjectIdentity" [editable]="true" [optional]="false" [completed]="selectedIndex > i"

<mat-horizontal-stepper [linear]="true" [selectedIndex]="selectedIndex"

<mat-step *ngFor="let step of steps; let i = index" [editable]="true" [optional]="false" [completed]="selectedIndex > i"

<mat-horizontal-stepper [linear]="true" [selectedIndex]="selectedIndex">
  <mat-step *ngFor="let step of steps; let i = index" [editable]="true" [optional]="false" [completed]="selectedIndex > i">

this.completedIndex = this.selectedIndex < this.data.steps.length - 1 ? this.selectedIndex + 1 : this.data.steps.length - 1;
setTimeout(() => {
  this.selectedIndex = this.completedIndex;
  this.cd.detectChanges();
});