Custom visuals shows 401 Un-authorized error in web application embedded reports

1. We are generating token by authorization code.

2. After authentication out of the box visualisation are visible but Custom visualisation throws 401 un-authorized error.

3. Please check image below for more details.

Image link

4. We are using sample power BI web application from github . Reference

5. Please provide a resolution for authorization problem with custom visuals.

Thanks