On July 12th, 2016, Microsoft released a security update which prevents Excel from reading workbooks exported from cloud based applications, like the Accord LMS, if the file is not opened from a folder that is not explicitly included in your trusted locations settings. Everything about the export and download process is working properly. The problem is that Excel simply won't open the workbook. The most frustrating aspect of this problem is that there is no message or indication that anything has gone wrong.
This short video
demonstrates three examples of the problem as it might appear and reviews your options to resolve the issue.
Fortunately, Microsoft has provided documentation to resolve this issue.
1. Apply the latest updates for your version of MS-Office.
2. You may want to add one or more trusted folders to your Excel Trust Center Profile.
Both of these processes are covered in the following Microsoft Knowledge Base Article: https://support.microsoft.com/en-us/kb/3181507
If, after following the directions in the Microsoft article, you are continuing to have problems with your Excel Report files, please have your technical folks contact firstname.lastname@example.org and we'll help you sort it out.