Excel Automation in C# - Excel process won´t quit

Hi there,

I´m using Excel automation with C#. When closing Excel, the Excel.exe process still remains in the Task Manager. I´ve tried all the topics that can be found, but Excel won´t quit. When I make Excel visible and close it myself, then the process will stop. But when I call the Quit() method, it keeps running.

Here is my code:

                Excel.Application oExcel = new Excel.Application();
                oExcel.Visible = true;
                Excel.Workbooks oWorkbooks = oExcel.Workbooks;
                string Pfad = "C:\test.xlsx";
                Excel.Workbook oWorkbook = oWorkbooks.Open(Pfad);

                Excel.Worksheet oSheet = oWorkbook.Sheets[1];
                
                oSheet.Cells[1, 1] = "Test";
                oSheet.SaveAs("C:\test.xlsx");

                GC.Collect();
                GC.WaitForPendingFinalizers();
                        
                Marshal.FinalReleaseComObject(oSheet);
                oWorkbook.Close();                
                Marshal.FinalReleaseComObject(oWorkbook);
                oExcel.Workbooks.Close();                
                Marshal.FinalReleaseComObject(oWorkbooks);
                oExcel.Application.Quit();                
                Marshal.FinalReleaseComObject(oExcel);
                oExcel = null;

Thanks for any help!