[ADGraphGroupOperationFailed] - Need Definition of this error!

We're tracking a strange issue in this ticket: 

https://community.powerbi.com/t5/Developer/ADGraphGroupOperationFailed-Error-while-embedding-a-report/m-p/534046/highlight/false#M16404

Can anyone please tell us what [ADGraphGroupOperationFailed] means.  We have no way to troubleshoot as this error message isn't giving us any workable understanding of the issue at hand.