gistfile1.cs

//Works
public async void Write(byte[] buffer)
{
    var len = buffer.Length;
    Size += len;
    await _stream.WriteAsync(buffer, 0, len);
}

var bytes = Encoding.UTF8.GetBytes(item);
blob.Write(bytes);  

//Doesn't work
public async Task Write(byte[] buffer)
{
    var len = buffer.Length;
    Size += len;
    await _stream.WriteAsync(buffer, 0, len);
}

var bytes = Encoding.UTF8.GetBytes(item);
await blob.Write(bytes);