Powerbi services refresh error with On-Premises gateway. DM_GWPipeline_Gateway_MashupDataAccessError

Powerbi report has SQL queries for pulling data from different data sources like db2 and Hana. It also used native SQL queries.

When I try to refresh the data manually in powerbi desktop, everything updates well. In services, using on premises gateway the refresh is getting failed giving "DM_GWPipeline_Gateway_MashupDataAccessError" error message. It also gave "DM_GWPipeline_Gateway_ImpersonationError" in the beginning before trying out other solutions. 

This is the complete error message.

Data source error{"error":{"code":"DM_GWPipeline_Gateway_MashupDataAccessError","pbi.error":{"code":"DM_GWPipeline_Gateway_MashupDataAccessError","parameters":{},"details":[{"code":"DM_ErrorDetailNameCode_UnderlyingErrorCode","detail":{"type":1,"value":"-2147467259"}},{"code":"DM_ErrorDetailNameCode_UnderlyingErrorMessage","detail":{"type":1,"value":"Native queries aren't supported by this value."}},{"code":"DM_ErrorDetailNameCode_UnderlyingHResult","detail":{"type":1,"value":"-2147467259"}},{"code":"Microsoft.Data.Mashup.ValueError.Detail","detail":{"type":1,"value":"#table({\"Name\", \"Data\"}, {})"}},{"code":"Microsoft.Data.Mashup.ValueError.Reason","detail":{"type":1,"value":"Expression.Error"}}],"exceptionCulprit":1}}} Table: XXXXX

Any help would be apreciated!