Ah, that's interesting, many thanks Little John. Actually, the non-updated Windows 10 system here didn't initially show my application's icon, but I believe that was because the system tray was cluttered already. The Windows Server system shows the full system tray anyway, which I prefer.
This application is due to be installed on a set of up-to-date systems anyway, including Windows 11. Fingers crossed, it will work. Thanks again.