Cannot create Pull Request

Hi there.
On a quite fresh gitea installation for the first time I want to merge two branches in one repository.
A pull request in the web interface seems the obvious thing to do. But I seem unable to create one.

So when I view the list of branches, there is a button “New Pull Request”. The pre-selected branches are good, so I press the “New Pull Request” button. On the next screen I can edit the title, but then the box “write” is empty, and what I am missing quite badly is something like “Submit Pull Request”.

I also checked Usage: Pull Request - Docs but the content there unfortunately does not mention at all how to create a pull request.

What may be missing?

edit: I resolved my situation now by merging the branch to master in git, then pushing again to Gitea.