Angular Recursive template using Pipe

I have a recursive angular template using Pipe. My problem is it only displays up to 2 level.

Pipe Converter

Here, recursively filter the data to find all children by parentid

@Pipe({ name: 'converter' })
export class ConverterPipe implements PipeTransform {
  transform(array: any[], parentId: string = "0"): any[] {
    return this.filterNodes(array, parentId);
  }
  filterNodes(array: any[], parentId: string): any[] {
    return array.filter((node) => { 
      return node.parent === parentId; 
    }).map((node) => {
      console.log("parentid > " + parentId)
      console.log(node)
      node["items"] = this.filterNodes(array, node.id); 
      return node;
    });
  }
}

HTML

Recursive template

  <ul>
    <li *ngFor="let item of mainmenu" >
      <a href="#" >{{ item.id }} {{ item.name }}</a>
      <ng-container *ngTemplateOutlet="List; context:{ $implicit: submenu , parentid: item.id, submenuclass:1 }"></ng-container>
    </li>
  </ul>
<ng-template #List let-items let-parentid="parentid", let-submenuclass="submenuclass">
    <ul>
        <li *ngFor="let item of items | converter: parentid">
          <a href="#">{{ item.id }} {{ item.name }} {{ parentid }}</a>
          <ng-container *ngTemplateOutlet="List; context:{ $implicit: submenu, parentid:item.id, submenclass:0}"></ng-container>
        </li>
    </ul>
</ng-template>

Typescript

Contains the data and 2 variables which separates the main menu from sub menu

  menu = [
    {
      "id": "32",
      "name": "System Admin",
      "parent": "0",
    },    {
      "id": "33",
      "name": "User Maintenance",
      "parent": "32",
    },
    {
      "id": "35",
      "name": "Back Office Users",
      "parent": "33",
    },
    {
      "id": "37",
      "name": "Portal Users",
      "parent": "33",
    },
    {
      "id": "36",
      "name": "Site Maintenance",
      "parent": "32",
    },
    {
      "id": "38",
      "name": "Sample",
      "parent": "35",
    },
    {
      "id": "39",
      "name": "Sample2",
      "parent": "35",
    }
  ];
  mainmenu;
  submenu;
  constructor() { }

  ngOnInit() {
    this.mainmenu = this.menu.filter( item => item.parent =="0")
    this.submenu = this.menu.filter( item => item.parent !="0")
  }

The last two data, "Sample" and "Sample2" is not showing under "Back Office Users" when I run the app.