We would need to have a copy, potentially, of the Excel sheet that you're using and the code you're attempting to execute.
My guess is that the excel sheet has formulas in the cells. I think (but I'm not certain) that there is some setting somewhere in Excel that automatically resolves formulas. This needs to be set so that the cells are resolved properly.
Of course, it depends upon how you are interacting with the spreadsheet. Again, your code would be a big help in understanding this.
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