Product:
Cognos Controller 10.3
Microsoft Windows 2012 R2 server
Microsoft Excel 2010

Problem:
Some excel reports show 0 when updated with F9 or F10. No errors, but the numbers are not shown.

Possible workaround:
Change the xls filename to not contain any Swedish Characters (åäö) or turn off the use of Optimise2 (ERO).
Previous it have been known that space or apostrophe in the excel workbook name or worksheet name can give issues when using ERO reports.

To turn off ERO go to cell A1 in Excel;
Click the tab ‘Formulas’
Click ‘Name Manager’
Highlight the entry ‘ Optimise2’ (which refers to Sheet1, cell A1)
Click ‘Delete’
Save the worksheet and try again.

Create a support ticket with IBM Cognos Support to get a better solution to this issue.

More information:
http://www.ibm.com/support/docview.wss?uid=swg21966485
http://www-01.ibm.com/support/docview.wss?rs=0&uid=swg21365263
http://www-01.ibm.com/support/docview.wss?uid=swg21607230