I am sorry for the delayed reply. We were trying to find a solution and help you work with sub-categories until we fix the issue.
What I can suggest for the moment:
Go to the News
widget for example, Select a parent category then go to Advanced
> Select Categorized
Get the sub-category UrlPath ID and replace the one that is already there.
Please, let me know if this is not working and you need further assistance.
the Telerik team
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