In most Windows 11 cases, you don’t actually need Fn for Shift+F10. Try Shift + F10 first. If that fails, disable Fn Lock in BIOS, and the key will work as expected.
Look for a key on your keyboard labeled "FnLock" or an icon of a lock with "Fn" inside it. It is often located on the Esc key. Press Fn + Esc to toggle the Function Key Lock. Test the shortcut again.
If none of these troubleshooting steps resolve the issue, you may want to consider resetting your Windows 11 device or seeking further assistance from Microsoft support.