How is the Project_Personalplanung in your first screenshot created (and saved)?

I assume you have filled al the items on all the tabs in the widget? 

Now it works. Thank you very much for your support.

Can you make a screenshot of the page you are using to show the Gant Chart?

EDIT:
I followed the steps provided by the creator of the widget and found out that it works like a charm. I can create a new task, i can see it in the widget. I can leave the page and return to Gantt page and still see the created tasks. 

Are you sure you have provided a Dataview in where you have the Project entity as a context object?

Hi Daniel,

What is not clear? Perhaps we can assist you on the unclear part :)

I dont have an overview about different “projects”. I got only one (not deletable) project

When i open the page, the following microflow will be triggered:

Is it possible to get your projectfiles?