I'm getting this exception in a Xamarin.Forms app while testing both Android and UWP projects. (No iOS test yet.)

When I debug in Visual Studio 2017/2019, the instantiated TransferUtility object does not list any of the expected methods.

All Nugets have been updated. The Aws Nugets are in the Forms project, and I also tried adding them to the Android and UWP projects as well.

• AWSSDK.CognitoIdentity v3.3.100.75
• AWSSDK.Core v3.3.103.39
• AWSSDK.S3 v3.3.104.27

Method not found: 'System.Threading.Tasks.Task Amazon.S3.Transfer.TransferUtility.DownloadAsync(System.String, System.String, System.String, System.Threading.CancellationToken)'.

Note that it's not just UploadAsync(), but also Upload() and I don't see any of the Download* methods either. As soon as I step into the the S3Upload method, I get the exception.

The code lives in the Xamarin.Forms project, is very basic, and it works for a stand alone Xamarin Mac application, but not for Xamarin.Forms:

    public async Task S3Upload()
    {
        try // The exception occurs as soon as I try to step into this method
        {
            // Initialize the Amazon Cognito credentials provider
            var credentials = new CognitoAWSCredentials(
                "us-east-1:not-my-real-id", // Identity pool ID
                RegionEndpoint.USEast1 // Region
            );
            IAmazonS3 s3Client = new AmazonS3Client(credentials, RegionEndpoint.USEast1);


            var filePath = [email protected]"path-to-the-file"; // not the real path, but we never get to this line

            var info = new FileInfo(filePath);

            var xfer = new TransferUtility(s3Client);
            //var xfer = new TransferUtilityUploadRequest
            //{
            //    BucketName = bucketName,
            //    Key = info.Name,

            //};

            if (info.Exists)
            {
                //xfer.Upload(filePath, bucketName);
                await xfer.UploadAsync(filePath, bucketName);
            }
            else
            {
                //xfer.Download(filePath, bucketName, info.Name);
                await xfer.DownloadAsync(filePath, bucketName, info.Name);
            }
        }
        catch (AmazonS3Exception amazonS3Exception)
        {
            if (amazonS3Exception.ErrorCode != null &&
                (amazonS3Exception.ErrorCode.Equals("InvalidAccessKeyId") ||
                 amazonS3Exception.ErrorCode.Equals("InvalidSecurity")))
            {
                Console.WriteLine("Please check the provided AWS Credentials.");
                Console.WriteLine("If you haven't signed up for Amazon S3, please visit http://aws.amazon.com/s3");
            }
            else
            {
                Console.WriteLine("An error occurred with the message '{0}' when writing an object", amazonS3Exception.Message);
            }
        }
    }

Any tips or pointers appreciated!