Using .Cells 7.1.0, I have an application that generates a spreadsheet that uses the NETWORKDAYS function. If I save to XLSX, everything's fine, but if I save to XLS I get #VALUE! in the cells that reference that function. If I select one of these cells and type F2/Enter, the error is corrected, so it appears the text of the formula itself is fine.
I have attached both an XLS and XLSX, indentically generated except for the save format.