Hi,
just figured out, that the same effect occurs when executing on the BI platform.
But this might be related to configuration of the BI platform as described in chapter 5.3.6 in the Admin Guide for DS 1.5 SP1:
https://websmp208.sap-ag.de/~sapidb/012002523100011445262015E/ds_15SP01_admin_bip_en.pdf