[ADGraphGroupOperationFailed] Error while embedding a report

Wow, this sounds strange. I hope this isn't something that continues to happen.

When you say "pull the report with Power BI Desktop", do you mean that your designer re-published the PBIX file back to the workspace using Power BI Desktop? The reason I ask is that Power BI Desktop cannot directly open a Power BI report inside the Power BI Service. You can only open a PBIX copy of the report in Power BI Desktop and then publish that PBIX on top of the current version of the same report in the Power BI Service inside target app workspace.

Was your experience that as soon as you republished the reports using Power BI Desktop, they begun to work correclty again in a Power BI embedding scenario? Is it possible your PBI designer did extra steps to fix the problem such as reset dataset parameters or datasource credentials?