Power Bi Report Server on premise host Excel workbooks

In our BI enviroment we have SharePoint  and Office Online Server who display the Excel reports

We are using also the PowerBI Report Server for display powerbi report

I have configured the OOS url inside the PoerBi Report Server settings

I have uploaded the Excel file but when I try to open I get the error File do not exists

This the error One Drive Error Print Screen

I have tried with a real Excel report who work from SharePoint using the same OOS server and with a empty blank excel. The same error.

I have tried on root or inside subfolders: the same error

Any suggestion?

Lorenzo