Microsoft Excel (2010) an existing spreadsheet is not updating links to a different spreadsheet.

Hello,

I have a user that is running Excel 2010.  She suddenly started reporting that a particular spreadsheet is not working correctly anymore.  This spreadsheet contains cells whose values are linked to a different spreadsheet.  I don't think there is a relation, but user started reporting this problem right after her Operating System was upgraded from Windows 7 to Windows 10.

For testing purposes, I had the user create a new Sheet within the spreadshseet and test.  The new sheet is linking fine.  I've also tried the same spreadsheet from a different PC.  The same issues are present from different workstations.  

I'm not very familiar with the inner working on Excel so my troubleshooting has been rather limited.  Is there anything you would recommend in terms of the troubleshooting approach?

Thanks in advance.

Regards,
Real-Timer