Power BI Service Dataset with Analysis Services data source, reports not working

Power BI Service Dataset with Analysis Services data source, reports not working. When attempting to analyze dataset with Report option, error message appears across the top of the screen, stating "this report couldn't access the data source. Contact the author to have it fixed". When using the Analyze with Excel option everything works OK.   This issue started last week with existing Datasets and reports, but only for those connected to Analysis Services. 

There is nothing in the Gateway logs to indicate any issues.

Premium Service, European Tenant, latest gateway installed.