没有看到纸质图标按钮图像

Question

我创建了一个带有2个纸质图标按钮的组件。这还包括铁图标。然而，当我点击虽然看到涟漪。图标图像本身丢失了。 这是代码

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<link rel="import" href="../../bower_components/polymer/polymer-element.html">
<link rel="import" href="../../bower_components/iron-image/iron-image.html">
<link rel="import" href="../../bower_components/paper-icon-button/paper-icon-button.html">
<link rel="import" href="../../bower_components/iron-icons/iron-icons.html">
<dom-module id="lightbox-app">
  <template>
    <style >
      :host {
        display: block;
        position: fixed;
        background: rgba(247, 245, 245, 0.8);
        width: 100%;
        height: 100%;
      }
    </style>
    <paper-icon-button icon="favorite"style="color: red;" title="heart"></paper-icon-button>
    <paper-icon-button  icon="arrow-back" style="color: rgb(10, 10, 10);"></paper-icon-button>
<iron-image   sizing = "cover" style = "width:calc(100% - 4px); height:180px; background-color: lightgray;"
preload fade src="https://firebasestorage.googleapis.com/v0/b/wishpix-5fff8.appspot.com/o/gn-01.jpg?alt=media&token=dd1a1f47-a2f8-464a-bb3c-0581ea7613d0"></iron-image>
  </template>
  <script>
    /**
     * @customElement
     * @polymer
     */
    class LightboxApp extends Polymer.Element {
      static get is() { return 'lightbox-app'; }
      static get properties() {
        return {
          prop1: {
            type: String,
            value: 'lightbox-app'
          }
        };
      }
        ready ()
        {
          super.ready();
        }
      
    }

    window.customElements.define(LightboxApp.is, LightboxApp);
  </script>
</dom-module>

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＆＃13; 如上所述，当点击时看到波纹时，看不到图像