GroupNotAccessible - Reports - Export To File In Group

Hi, 

I'm trying the api here using:

https://docs.microsoft.com/en-us/rest/api/power-bi/reports/exporttofileingroup#code-try-0

But I"m getting the error GroupNotAccessible.

I checked that I'm a member of the Group that owns the Report and the Dataset. 

Kindly advise. 

Thanks.