Hi @Nayan Das
Welcome to Microsoft Q&A! Thanks for posting the question.
This might happen when the query/parameters used is incorrect. Do you still see that the operation has not been completed using query in Log Analytics Workspace (i.e., the records that needed to be removed are still present)?
Also, please check the "Activity logs" for the targeted workspace. It should contain the operation details along with failure information, if any.
Please let me know if you have any questions.
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