Power BI Embed Not Render All Reports from Workspace

My team is developing a Web App (Backend: Django - Frontend: React) to consumes reports of Power BI Service. We are using the AppOwnData Embed in specific the "Get embed params for multiple reports for a single workspace" services. (https://github.com/microsoft/PowerBI-Developer-Samples/blame/f78ad3006861a82b13276d8ecba1c5e6688c6e0e/Python/Embed%20for%20your%20customers/AppOwnsData/services/pbiembedservice.py#L45) 

But only the last report that requests the token is rendering, the others report are only showing the title and the following error message. 

Failed to load resource: the server responded with a status of 403
POST https://wabi-paas-1-scus-redirect.analysis.windows.net/explore/conceptualschema 403

We already follow all the steps to set up the AAD (https://docs.microsoft.com/en-us/power-bi/developer/embedded/embed-service-principal) so there isn't any problem. 

We wonder what could be missing or what it could be wrong. We need that all the reports requesting the token can render successfully