The common reason for such issue is when the page loads multiple versions of Telerik Kendo UI files or jQuery or the same file more than ones.
Please check what Kendo CSS and JS files are loaded, and if they are of the same version.
Most probably files are loaded from several locations - the page, bundles and/or the layout page.
If the above information does not solve the issue, please send us a demo project to check your settings.
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