Google Model Viewer Not Showing In the Development

I use Google Model Viewer in My Website Project to show a model on the homepage. However, in the development stage, the model is not shown on the page. But when I deploy the same website on the netfily, the model show after a negligible amount of time. Can anyone tell me why this Happened? I use CDN of Google Model Viewer and a simple Handset 3d model to show on the homepage.