CQ5.5 DAM - Corrupted Zip Download from Asset Share page

As can be seen in the attached screenshot, when I go to the asset share page, select an item and click download, I am prompted to download a zip file. I download it and when I try to unzip this zip file, receive an error popup that says "Unable to expand %FILENAME% to %LOCATION%".

Any ideas as to why this download functionality would be broken? I've tried on both Windows and Mac just to try to rule out some possibilities. Also, I tried on a separate CQ5.6 DAM and found that to work properly by downloading and then unzipping.

Thanks, Tom