Hello David,

I logged an internal issue with Development ID 213539 so that we can fix it in our codebase.
I also created a case on your behalf with number CAS-169366-Z9S2H4 , so that you can be notified when there is a resolution for the issue.
You can find your active cases under Account - Support Activity in our website. Select your ticket and go to Development Issues tab to view the status of related development issues.

You can try to work around it by sending the file name separately as part of the request as described in this topic "Using Server-Side Events in ASP.NET MVC (igUpload)" section "Sending additional data between the client and server during file uploading". On the server you should rename the file with the correct name in the UploadFinished event.

Here is an example code:

On the client in JS:

 
$("#upload1").on("iguploadonformdatasubmit", function (evt, ui) {
            $("#upload1").igUpload("addDataField", ui.formData, { "name": "fileName", "value": ui.fileInfo.file.name });
});

On the server in C#:

public static void igUpload_UploadFinished(object sender, Infragistics.Web.Mvc.UploadFinishedEventArgs e)
{
    var fileName = e.AdditionalDataFields[0].Value;
    System.IO.File.Move(e.FolderPath + e.FileName, e.FolderPath + fileName);
}

Best regards,
Martin Pavlov
Infragistics, Inc.

The fix for development issue 213539 is available in the latest service release which can be downloaded from the My Keys and Downloads page.