Serilog Cloudwatch logging not enriching the logs

I have used Serilog in the past and enriched logs with various properties. However I am playing around with the new AWS Lambda Serverless templates using .net core 3.1 and cannot get the logs to enrich. I have tried this in a basic Console app as well with the same result.

Example: code:

class Program
{
    static void Main(string[] args)
    {
        Log.Logger = new LoggerConfiguration()
            .MinimumLevel.Debug()
            .WriteTo.AWSSeriLog(GetAwsSerilogConfiguration())
            .Enrich.FromLogContext()
            .Enrich.WithMachineName()
            .CreateLogger();

        using (LogContext.PushProperty("A", 1))
        {
            Log.Information("Starting web host");

            Console.WriteLine("Hello World!");
        }
    }

    private static AWSLoggerConfig GetAwsSerilogConfiguration()
    {
        var environmentName = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
        return new AWSLoggerConfig
        {
            LogGroup = $"AwsLoggingTestConsoleApp/{environmentName ?? "Development"}",
            Region = RegionEndpoint.APSoutheast2.SystemName
        };
    }
}

The following screenshots from Cloudwatch Logs and Insights show the log generated by this code. The enriched property 'A' and MachineName do not appear

Cloudwatch Logs

Cloudwatch Insights

I feel like I am missing something obvious, but for the life of me I cannot see it.

Any ideas why the logs are not being enriched?

Many thanks,

M.