PyCharm does not create tests

I have a relatively fresh isntallation of pycharm 2017.3.3 and set the default test runner to Unittest in the settings. However, when I right-click on a class, click "Go To"->"Test" and in the appearing window click "Create New Test" nothing happens.

I do not get an error message or indication of what I did wrong.

Did I forget to set something up?