During my own attempt to solve a problem similar to yours, I found two methods that might assist you.
Firstly, ensure that the folder where your desired icon is located does not contain any emojis. Windows may struggle to recognize the file path if the folder or file has an emoji. For example, "C:\Users\ajaero\Downloads". If this method works, then that is the issue.
Secondly, if the folder where you intend to change the icon contains the desired icon, move it to a different folder. This might be the cause of my folder having an emoji in the name so this is most like not the answer