Can you provide more information/clarification on the issue you're experiencing? Also, what version of Pega Knowledge are you using (e.g. 7.1.1, 7.21?). Are you seeing any errors (if so, please add them to this thread). -Thanks!
Issue was resolved. They have limit of adding 500 only when we exceeded that limit, parent categories created are being deleted. Now we changed the limit to more which will fulfil our requirement. Thanks though.