primeng drop down inside prime ng table selection disappears when adding new row

[u4u]

"primeng": "6.1.3",
angular 6.1.9

<p-dropdown [autoWidth]="false" (ngModelChange)="onModelChanged($event)" appendTo="body" [options]="rowData.companyList" [(ngModel)]="rowData.selectedCompany" placeholder="Select a company" optionLabel="name" name="selectedCompanyId"></p-dropdown>

[u4u]

where can i find a link if it is duplicate