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Do you want to request a feature or report a bug?

• Bug
• Feature
• Question

Did you test against the latest CI build?

• Yes
• No

If you answered No, please test with the latest development build first.

Version of ClosedXML

0.100.3

What is the current behavior?

When using UNIQUE formula adds @ to start of formula breaking its usage.

What is the expected behavior or new feature?

I expect the formula to no have the @ symbol prepended

Is this a regression from the previous version?

NO

Reproducibility

Code to reproduce problem:

public void Main()
{
            using (wb = new XLWorkbook())
            {
                var sheet = wb.Worksheets.Add("UNIQUEFORMULAEXAMPLE");
                sheet.Cell(1, 1).Value = "1";
                sheet.Cell(2, 1).Value = "2";
                sheet.Cell(3, 1).Value = "3";
                sheet.Cell(4, 1).Value = "4";

                sheet.Cell(1, 2).FormulaA1 = "=_xlfn.UNIQUE(A1:A4)";

                wb.SaveAs("Test.xlsx");
            }
}

• I attached a sample spreadsheet. (You can drag files on to this issue)
  Test.xlsx