Registering a Serilog file logger for dependency injection in a .NET Core 3.0 WinForms application

I am having difficulty writing to a log file with Serilog. I have posted my issue on StackOverflow here but haven't been able to get to the bottom of it. Is anybody here able to help, please?

I am developing a WinForms application in .NET Core 3.0. I would like to log debug information to a file. I'd like to get a reference to my logger in various classes using dependency injection.

Most of the articles and documentation I found focused on ASP .NET rather than WinForms, so I had to use my imagination a bit when setting up Serilog in my Program's static void Main() method.

public class Program
    {
        private static Logger _logger; // I noticed that you don't have to do
                                       // this in the ASP .NET samples as it's
                                       // taken care of "under the hood".
                                       // However, I couldn't see any
                                       // alternative in the standard
                                       // WinForms template in VS.

        private static void Main()
        {
            //Omitted some code about configuration files and WinForms initialization for brevity

            var services = new ServiceCollection();
            ServiceProvider = ConfigureServices(services);

            Application.Run(Form1);
        }

        public static IServiceProvider ServiceProvider { get; private set; }

        private static ServiceProvider ConfigureServices(IServiceCollection services)
        {
            services.AddLogging(loggingBuilder => loggingBuilder.AddSerilog(GetLogger(), true));
            GetLogger().Critical("Hello!!"); // Just testing... nothing happens. Where's my log file?
            //Omitted registration of various unrelated services for brevity

            return services.BuildServiceProvider();
        }

        private static Logger GetLogger()
        {
            if(_logger is null)
            {
                _logger = new LoggerConfiguration()
                .WriteTo.File(@"c:\BenjaminLog.txt", restrictedToMinimumLevel: Serilog.Events.LogEventLevel.Debug, rollingInterval: RollingInterval.Day)
                .CreateLogger();
            }

            return _logger;
        }
    }
}

This code builds and runs without exception but no log file is generated on c:\ What did I do wrong?

serilog / serilog-extensions-logging

Registering a Serilog file logger for dependency injection in a .NET Core 3.0 WinForms application #146