Thanks for posting your question in the Microsoft Q&A forum.
Sometimes transient issues occur during the process. Retry enabling diagnostic settings for your Key Vault. Ensure that you have the necessary permissions to configure diagnostic settings. Ensure that there are no resource locks or policies preventing changes to the Key Vault. Check if any Azure Policy or custom RBAC permissions are restricting the modification of diagnostic settings.
Visit the Azure Service Health page to check if there are any ongoing issues or outages affecting the Azure services, including Azure Security Center. If there are any service disruptions, wait until they are resolved and then try again. Azure services can sometimes experience transient issues, and retrying the operation after a short interval might resolve the problem.
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