It seems that the styles and the scripts used for the RadMenu control are not applied and thus you get the appearance. Please check if there is any javascrip error on the page that might be causing the issue. Can you also clarify if this happens on your local machine only or when you deploy your site on a production server. You could also try using our CDN provider
and check if this resolves the issue for you.
All the best,
the Telerik team
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