Error log from the EPM Log option:
2016-06-03 15:02:43,294|ERROR|BPCProxy|FPMXLClient.BPCProxy.Common.Wcf.InterceptorChannelFactory`1+InterceptorRequestChannel.Request|USERID|||||1|The remote server returned an unexpected response: (400) Bad Request.#
2016-06-03 15:02:43,294|ERROR|Dataservice|FPMXLClient.BPCProxy.MetaData_Data.DataServiceHelper.ExecuteCellQuery|USERID|||||1|The remote server returned an unexpected response: (400) Bad Request.#
2016-06-03
15:02:43,294|ERROR|BPC10Connection|FPMXLClient.Connection.RESTConnection.RetrieveData|USERID|||||1|The remote server returned an unexpected response: (400) Bad Request.#
2016-06-03 15:02:43,294|ERROR|FormattingSheet|FPMXLClient.Office.EPMExcelSheet.RefreshData|USERID|||||1|Error in RefreshEVFunctions - Data partThe remote server returned an unexpected response: (400) Bad Request.#