Hello Christoph, the hint helped, now we get a response! Thank you!
When we create a business partner with an address in SAP, it is created and saved. We did it like this: SE37 > Function Module (Menu) > Execute > Test Sequence. First BAPI_BUPA_CREATE_FROM_DATA and then BAPI_TRANSACTION_COMMIT executed one after the other.
On the other hand, if we execute the same data in the Simplifier as a sequence, unfortunately it will not commit. To do this, we have configured the connector so that BAPI_BUPA_CREATE_FROM_DATA with [0]/… should be executed first and then BAPI_TRANSACTION_COMMIT with [1]/… (also the output parameters). We even receive a response with the generated business partner number. However, this is not finally saved.
Are two individual sessions started on SAP? I believe it is important that both BAPI calls run within a single session.