Th reason could be in the URLs, which needed be changed. You didn't posted enough code detailed, which could shows what you do exactly. I' recommend you to read the post first of all.
Moreover I would recommend you to consider to use some CDN source for loading jQuery, jQuery UI and jqGrid files. The first loading of data from CDN will be quickly enough and later the data will be mostly hold in the cache of the web browser, thus there will be not loaded more. Moreover, jQuery and jQuery UI, Bootstrap and so on will be used by the most web sites and many sites use the same CDNs as you. Thus one have higher probability, that jQuery and jQuery UI are already in the cache of the web browser event at the first loading of the files. As the result the user will see the best performance typically in case of usage URLs from CDN. I personally think that one should include in the bundle only your custom JavaScript/CSS files, which you could changes more frequently.
The next version of ASP.NET and MVC (ASP.NET 5 with MVC 6) recommend to use CDN source as the first and the use local JavaScript files for the fallback scenario:
<script src="//ajax.aspnetcdn.com/ajax/jquery/jquery-2.1.4.min.js"
asp-fallback-src="~/lib/jquery/dist/jquery.min.js"
asp-fallback-test="window.jQuery">
</script>
See the article.
By the way the wiki article describes the URLs to free jqGrid.