Xcode 11.2.1 - Table view is not working after update

Question

I am developing a little app where you can add notes to a list using core data. It used to work perfectly fine until the last update to Xcode 11.2.1. Usually, every note appeared in the tableview right after adding it. After the update it did not work at all. I noticed that every new project in 11.2.1 contains a new file called "SceneDelegate". I copied and pasted the file into my project. But every added note will only appear once you restart the app. Does anybody know how to fix that?