TABLES parameter on SOAP web service is not populated when called from HCI

Dear all,

I am building a data flow from HCI into APO, based on this great article: https://blogs.sap.com/2016/12/05/export-data-from-sap-ibp-to-sap-apo-through-hci-ds-via-web-services/.

My case is very similar, except my web service calls a simple Z RFC function module with a TABLES parameter (so no BW / BI involved). The service is registered as a datastore, and the data flow (validation returns no message whatsoever) looks like this:

Characteristics table with 3 entries -> Query -> Batch -> XML Map -> Web Service

When I run the data flow, the service is called, but the tables parameter is always empty (I know this because it writes the time stamp and lines of the parameter into a database table). The monitor log shows Row Count = 3 for the steps before and including the XML map, and Row Count = 1 after, butthe tables parameter is never populated. Calling a service that has import parameters only, however, works fine (without the Batch in the dataflow).

Do you have an idea what might be wrong here?

Thanks and regards,

Max