Refresh not possible with enhanced Metadata after latest Update

I installed the latest update of PBI-RS from January.

For some reason I cannot reply to the post about this update (https://community.powerbi.com/t5/Report-Server/Power-BI-Report-Server-October-2020-update-2/m-p/1588156#M17414)

I have issues like those reported here: https://community.powerbi.com/t5/Report-Server/Power-BI-Report-Server-October-2020-update-has-been-released/td-p/1503433

I import several Excel files from a Folder.

Data Refresh was not possible until I updated PBI-RS to the January Patch.

I think due to problems with different casing in the path, which is corrected in this update as documented in the changelog (

https://docs.microsoft.com/en-us/power-bi/report-server/changelog)

Now the data refresh stops with the following error message in the RSPowerBI_xxx.log:

2021-01-13 12:09:21.5116|ERROR|59|Error Processing Data Model Refresh: SessionId: e22bf2be-0ffd-49c0-bf79-ecf506e9b2c7, Status: Error Failed Data Refresh, Exception Microsoft.AnalysisServices.OperationException: Failed to save modifications to the server. Error returned: 'COM error: Microsoft.PowerBI.ReportServer.ASEngineManagedRoot, An item with the same key has already been added..
The current operation was cancelled because another operation in the transaction failed.
'.
at Microsoft.PowerBI.ReportServer.WebHost.EventHandler.DataRefreshScope.ExecuteActionWithLogging(Action methodToExecute, String description, String localizedDescription, String messageInFailure, RefreshInfo refreshInfo, DataAccessors dataAccessors, ReportEventType operation, Boolean isDataRetrieval, Boolean showInExecutionLog, Boolean sendToTelemetry)
at Microsoft.PowerBI.ReportServer.WebHost.EventHandler.AnalysisServicesDataRefresh.RefreshData(RefreshInfo refreshInfo)
at Microsoft.PowerBI.ReportServer.WebHost.EventHandler.DataRefreshScope.<>c__DisplayClass34_0.<ExecuteActionWithLogging>b__0()
at Microsoft.PowerBI.ReportServer.WebHost.EventHandler.DataRefreshScope.<ExecuteFuncWithLogging>d__33`1.MoveNext()

Update in PBI Desktop works without any issues.

After reading the posts mentioned above, I disabled the Enhanced metadata format and started from scratch.

I copied the M-Code from the original file, to have the identical transformations. Then I added the calculated columns to the models and deployed the new PBIX file to PBI-RS.

Now the Refresh works.

It looks like the enhanced metadata format is not implemented correctly in PBI-RS.

Is there an fix coming with the Official January Release of PBI-RS?

Best regards

Salvatore