Dear Gail, thank you for your reply.
Please see a running test here:
https://mygit.th-deg.de/tlang/hhh-12119

Please mind that this is our public git(lab) system. I haven´t used github as i have no account there.
However you should be able to clone the repository.

Without the use of Spring (Data JPA) i cannot clarify the issue.
The test runs and yields results, but my primordial problem is not depicted.

Please see the README.md as well.
I hope this helps you finding the issue.
Please let me know if there is something missing ok?

Thank you for your help!
Kind regards!
Thomas