Hello,
Sorry to hear you are having issues. But, from what I know, Icons developer is just an Icon maker/editor software. It is not for changing icons. As for icon changing. That will be control by Windows itself or other software such as Stardock IconPackager.
May I know, which desktop icon, you specifically trying to change? I will try to change it and see if the issue also appear on my system. Do know, Microsoft changed and block lots of places that we can no longer customize it ourself.
Thanks.
Basj,
Stardock Community Assistant.