Error 'Couldn't load the data for this visual' w/ Measures from DirectQuery for SAP BW BEX Query

Hi v-huizhn-msft, the feature "Live/DirectQuery to SAP BW" from the link you posted was implemented in june. The error I reported in this thread is about an error that is triggered when this featured is used and after only the report with DirectQuery and therefor Data Gateway connection is upload to Power Bi service. The metrics cause the report to throw the error message  "MdxScript(Model) (5, 42) Cannot find data source '' in function 'EXTERNALEXPRESSION'". Note that this error does not happen to any dimensions  nor the same error happens with the metrics when the report is being created in Power BI desktop.

Can you please point out a link where the issue can be officially reported to MSFT, once the option "Send a Frown (Error)" is not available in the error message window to report the technical issue. This seems to be an important issue related to the DirectQuery (beta) that would be worth reporting to the developers. 

Thank you. 
Blackj.