Cisco Exam 200-201 Topic 6 Question 38 Discussion

An employee reports that someone has logged into their system and made unapproved changes, files are out of order, and several documents have been placed in the recycle bin. The security specialist reviewed the system logs, found nothing suspicious, and was not able to determine what occurred. The software is up to date; there are no alerts from antivirus and no failed login attempts. What is causing the lack of data visibility needed to detect the attack?