x-docusign-signature headers not included in the eventnotification webhook request

Im using envelope level connect keys and setting the includeHMAC to true in the eventNotification object of the envelope.

This works and the x-docusign-signature headers are being sent as part of the call. We are using this with a client and initially the x-docusign-signature headers were coming through. But the x-docusign-signature headers are no longer present. Ive checked with our client and the connect key still exists for that account.

Is there any reason or a configuration setting that would stop the headers coming through?