After a successful build, the widget doesn't appear

I am trying to display the default implementation of the widget in the xcode 12 beta 3 and beta 4, if I create a new project, the widget is displayed successfully, but in the project of our company, after a successful build, the simulator starts and after nothing happens. I don't see any difference in the codebase of the widget classes.

Also the preview doesn't work for me, I get the following error:

RemoteHumanReadableError

ProcessError: Failed to launch widget extension: The operation couldn’t be completed. (Foundation._GenericObjCError error 0.)

But if I create a project from scratch, then the preview works well.