As we use localization for all strings used by the UI of the control, a probable reason for this behavior is that some of them are missing. If you have changed the files responsible for the localization or added new ones, please check if there is a string with key "Ok".
If this is not the case in your application, we would appreciate it if you could open a support ticket and enclose a demo project, so that we can narrow down the cause of the issue.
the Telerik team
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