When I tried to add the .ico file, I did get the error you mentioned after building:

According to the error message, I copied and pasted the Resources folder to the Properties folder and tried to build again, and it was able to see that the project was built successfully:

I suggest you try the above behavior again to see if it works. I think this is a VS issue. If you still encounter this issue after trying it, you can report this issue to DC. There are many VS developers who can help you.