There seems to be an error in the data registration, it is possible that something was done wrong when transferring the relations.
Do you use your own print loop or do you use databinding?
Please check whether the child table has different data records when you add the table as single element.
In the project I can see that the file was created with 25.001, if not already done I would recommend you to install the service pack for version 25 and test the behavior again.