Confluence - startDate parameter in the audit log API not honored

I am trying to get the Audit logs using the REST API available Get Audit Records and I am passing the startDate query parameter.

However, I see that I am getting the entire audit logs present (the result count is matching with the entries that I see in the Audit Logs web page).

Is there a way to get the audit logs only for a specified duration? (In my example, my last audit log entry was made on Feb 1st and I have passed the time stamp for Feb 4th as the start date, but I still see all the audit logs).

Thanks
Ravi