From the stack trace it seems you are using Razor components that use our components in an MVC app, so I suggest you review this example, its readme file and code comments on this scenario: https://github.com/telerik/blazor-ui/tree/master/common/razor-components. The key thing is that you need to have the TelerikRootComponent in each individual razor component because they are scoped and cannot find instances higher in the hierarchy.
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