Cannot load appsettings.json after converting .NET Core 3.1 console application to .NET Core 3.1 WinForms application

There was a console .NET Core 3.1 application for SOAP communication based on IHost / IHostBuilder.

Empty DataGridView cells after binding to List

I am binding a List to DataGridView:

How to send serialized JSON data in TCP/IP using C#?

What is the correct way to send serialized JSON data in C#