Filter not work when text changed on autocomplete text box angular 7

Question

I work on autocomplete text box on angular 7 I face issue when I write on text box

 

search or filter not work and not give me result .

 

actually when I write on text box auto complete related data must display but this not happen .

class deliverysys.ts
export class deliverysys {
constructor(public optionId: number, public optionName: string) { }
}

DeliverySystemComponent.ts
export class DeliverySystemComponent implements OnInit {
myControl = new FormControl();
ExportOptions: deliverysys[];
constructor(private http: HttpClient,private _dataService: DeliverySysService) {
this._dataService.getExport().subscribe(data => { this.ExportOptions = data
console.log(this.ExportOptions)
});
}
getselected(value,index) {
console.log("selected is" + index)
}
}

this display data as below :

this.ExportOptions
(5) [{…}, {…}, {…}, {…}, {…}]
0: {optionID: 1, optionName: "Export"}
1: {optionID: 2, optionName: "Export Normalized"}
2: {optionID: 3, optionName: "Export Normalized New"}
3: {optionID: 4, optionName: "Export Normalized Relation"}
4: {optionID: 5, optionName: "Export Nxp Comptitor"}

DeliverySystemComponent.html
<mat-form-field class="example-full-width">
<input type="text" placeholder="Select Exporter" aria-label="Number" matInput [formControl]="myControl" [matAutocomplete]="auto">
<mat-autocomplete #auto="matAutocomplete" >
<mat-option (click)="getselected(exp.optionName,i+1)" *ngFor="let exp of this.ExportOptions;let i = index" [value]="exp.optionName">
{{exp.optionName}}
</mat-option>
</mat-autocomplete>
</mat-form-field>

as you see image below when write any text not found

not give me not found

also if word I write found auto complete not changed and not give me related result

so How to solve issue of not displaying data related when I write or filter data ?