Brian,
Thank you. I think my problem is, that I only have one page for my module and therefor only one item in the UI Interface tree.
After adding a parent page, which is just using the vertical tabs layout, I'm able to see the title and pin-icon in the header.
EDIT: I think the problem might be more related to me using a build-in template for the parent page, wheras the other page was using the custom UI with a URL.