Child / Parent Relationship in SalesForce Input step

Hi everyone,

I am currently struggling with the Salesforce Input step of my transformation.
I started with a pretty simple query that won't give me the Parent Casenumber even though this should work (and is working for example when I did some testing with soapUI)

Select CaseNumber, Parent.CaseNumber from Case

It will return the CaseNumber but won't give me any values for the Parent.CaseNumber (just stays null) even though there are Cases that definitely have Parent-Cases.

Any help is appreciated :)