After an initial test, I can notice the issue by running your project and saving to XLS file format (XLSX format works fine though). I suspect it might be due to some PivotTable styles of your Excel 2007/2010 XLSX that are not supported in Excel 2003 XLS file formats, you may confirm this re-saving the XLSX file to XLS in MS Excel manually. Anyways, we need to look into your issue soon.
I have logged a ticket with an id “CELLSNET-41325” for your issue. Our concerned developer will look into it to figure it out soon.