Neither of these two options work for me either:
ShellExecute("Excel.exe", '"C:\Users\My User\Desktop\Book1.xlsx"', "", "", @SW_MINIMIZE)
ShellExecute('"C:\Users\My User\Desktop\Book1.xlsx"', "", "", "", @SW_MINIMIZE)
Windows 10 latest, Excel 365. It opens the file in Excel, but Excel is not minimized. @SW_MAXIMIZE does work.
The only way I can ensure that Excel is minimized is by minimizing it separately:
ShellExecute ("Excel.exe", '"C:\Users\My User\Desktop\Book1.xlsx"', "", "")
WinActivate ("Book1.xlsx - Excel", "")
WinWaitActive ("Book1.xlsx - Excel", "")
Send ("#{DOWN}")
or:
ShellExecute ("Excel.exe", '"C:\Users\My User\Desktop\Book1.xlsx"', "", "")
WinWaitActive ("Book1.xlsx - Excel", "")
WinSetState ("Book1.xlsx - Excel", "", @SW_MINIMIZE)