Link to pivot table data
 

One of my colleagues has a worksheet where cells are linked to data into
pivot tables created in external documents.

She has not made changes to the external document with the pivot tables.
Despite this, when she refreshes the data in the new document, it somehow
resets the cell reference to $A$2 and gives her a "#Ref" error in the cell.

Can someone explain what is causing this and how to get around it?