Are you sure your user/customer isn't using "User Filters". If so, you must authenticate against their server so that the filter can understand what you should and shouldn't be allowed to see. If you "Cancel", then you're not authenticating, and you choose to see nothing.
I understand you can't post the workbook, but you might be able to figure out what they're up to by following these steps:
- Make a copy of the twbx file and rename it to .zip
- Open the zip file and pull the .twb out of the archive
- Open the twb file in notepad or any text editor
- Use the text editor to "Find" references to the server name.
What are those references associated with?
- Or, just ask the user