This is working as designed and in order to generate an audit event, the API key must not attempt to reconnect until after the 30 minute timeout has expired. That way a new session will be started and new Audit log event will be created like this:
"<TIME><DATE> <API Key> Connector <API Key> logged in successfully"
However, the "LAST REPORTED TIME" for the API key in the API Access page of the Carbon Black Cloud console continues to work as an indication the last time that key successfully connected to the backend.