Hello
I've uploaded project where I can reproduce this error to GitHub
https://github.com/vospitannikov/PowerBIGroupReportIntegrationError
Please pay attention to "TODO" comments in order to set all needed data
Also, you need to create PowerBI application before running this project
You need access to some PowerBI group with report
1. access to some PowerBI group with report (in order to reproduce this error)
2. some not group report (in order to see that it works fine for general reports, not group one)
Please let me know if you can reproduce this error