I've researched this more. One thing I did wrong before was just copying the files from my Visual Studio project. I should have done a publish. (It's been a while since I created a web site.) After publishing, I don't even see the Telerik menu control.
I tried a few things that people said to do.
1. In the BundleConfig class - add bundles.IgnoreList.Clear() and bundles.DirectoryFilter.Clear()
2. In the Global.asax.cs class add BundleTable.EnableOptimizations = true;
I've tried publishing in both Debug and Release mode. But no difference.
At this point, I'm not sure what else to try. Any ideas?