Strange Behavior in ALV IDA when aggregating

I use the ALV IDA for consuming a HANA CalcView via External View in ABAP.

Aggregation works for 2 columns, but when it comes to aggregation on the third column, the list produces additional empty lines.

Is there someone facing the same problem ?

Additional x lines when it comes to third aggregation.

System ist SoH  Netweaver Relase 740 SP 4 / SP 6 for UI

Regards

Marko