//laravel mix has be generate links like below. Check your html output that is correctly generated links like this.
<script src="/js/app.js?id=0441ad4f65d54589aea5"></script>
and your /public/mix-manifest.json file must look like this;
{
"/js/app.js": "/js/app.js?id=7399f803fb3a155486e9",
"/css/app.css": "/css/app.css?id=6bea0cea688d689be1b1"
}
//If it is not like this an seems like this;
{
"/js/app.js": "/js/app.js",
"/css/app.css": "/css/app.css"
}
//Your webpack.mix file is wrong.