Using memory stream instead of filestream for AWS C# S3 SDK not returning full file

Question

I have some code that is meant to retrieve a file from an S3 bucket and deserialize the file. When I use a file stream I get all the data no problem, but when I use a memory stream it seems like I am not getting all of the data:

It doesnt get the full XML:

Where it should look like:

Here is the code I am using:

internal object ReadDataContractFromFile(string filename, Type type)
    {
        GetObjectRequest getObjRequest = new GetObjectRequest();
        MemoryStream memoryStream = new MemoryStream();
        getObjRequest.BucketName = bucketName;
        getObjRequest.Key = filename;

        string path = @"C:\{PATH_TO_FILE}\requests\" + filename;
        FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.ReadWrite);

        using (GetObjectResponse getObjRespone = s3Client.GetObject(getObjRequest))
        using (Stream responseStream = getObjRespone.ResponseStream)
        {
            responseStream.CopyTo(fileStream);
            //memoryStream.Seek(0, 0);
            XmlReaderSettings rs = new XmlReaderSettings
            {
                ConformanceLevel = ConformanceLevel.Fragment,
            };
            XmlReader r = XmlReader.Create(fileStream, rs);
            return new DataContractSerializer(type).ReadObject(r);

        }
    }

If I use memoryStream in place of the fileStream variable, I get the incomplete XML I showed above. I tried to seek to the beginning of the stream incase the position was wrong but that didnt fix it. Any idea what Im doing wrong?