MyWebPartWorkaround.ts

// remove everything else in constructor, except the super call
public constructor(context: IWebPartContext) {
  super(context);
  this._id = _instance++;
}

// create your own 'init' function, to be called a little later in the lifecycle:
 private doInitStuff() : void
    {
      const tagName: string = `ComponentElement-${this._id}`;
      const componentElement: HTMLElement = this._createComponentElement(tagName);
      this._registerComponent(tagName);
      this.domElement.appendChild(componentElement);

      const bindings: IHelloWorldBindingContext = {
        description: this.properties.description,
        shouter: this._shouter
      };

      ko.applyBindings(bindings, this.domElement);

      this._koDescription.subscribe((newValue: string) => {
        this._shouter.notifySubscribers(newValue, 'description');
      });
    }

// update the render method to do init too
public render(): void {
  if ( !this.renderedOnce )
  {
    this.doInitStuff();
  }

  this._koDescription(this.properties.description);
}