动态加载xr-ar-tracker和xr-asset-load?

Component:

<xr-scene ar-system="modes:Marker" bind:ready="handleReady">
  <xr-assets wx:for="{{trackers}}" wx:key="id" bing:loaded="handleAssetsLoaded">
    <xr-asset-load type="gltf" asset-id="{{item.modelName}}" src="{{item.modelSrc}}" />
  </xr-assets>
  
  <xr-node id="container" wx:if="{{loaded}}" wx:for="{{trackers}}" wx:key="id">    
    <xr-ar-tracker mode="Marker" src="{{item.trackerSrc}}">
      <xr-gltf node-id="{{item.modelName}}" model="{{item.modelName}}" />
    </xr-ar-tracker>
  </xr-node>


  <xr-light type="ambient" color="1 1 1" intensity="1" />
  <xr-light type="directional" rotation="40 70 0" color="1 1 1" intensity="3" cast-shadow />
  <xr-camera clear-color="0 0 0 1" background="ar" is-ar-camera />
</xr-scene>

Component (TS):

handleAssetsLoaded:function(){
      console.log("Done")
      this.setData({
        loaded:true
      })
    }

Data :

const trackers = [
      {id:0,modelName:"test1",
      trackerSrc:"https://mmbizwxaminiprogram-1258344707.cos.ap-guangzhou.myqcloud.com/xr-frame/demo/portalImage.jpg",
      modelSrc:"https://mmbizwxaminiprogram-1258344707.cos.ap-guangzhou.myqcloud.com/xr-frame/demo/damage-helmet/index.glb"},
      {id:1,modelName:"test2",
      trackerSrc:"https://mmbizwxaminiprogram-1258344707.cos.ap-guangzhou.myqcloud.com/xr-frame/demo/wxball.jpg",
      modelSrc:"https://mmbizwxaminiprogram-1258344707.cos.ap-guangzhou.myqcloud.com/xr-frame/demo/miku.glb"},
    ]

    this.setData({
      trackers
    })

问题：真机调试时，无报错，也没有打印“Done”。想了解XR-Frame怎么做动态加载tracker和资产