Below are the instances where malware may not be detected:

• If an anti-virus application or a DLP(data loss protection) application is installed on the remote side, a malware file in the remote side may not be detected.
• The Manual/Schedule Network File Scan impersonates the current scanning thread from a system privilege to a user privilege to access remote files. The user is the first one who opens the windows explorer. Therefore, as long as the user, who is the first one to open Windows Explorer, has no right to access the remote files, the network file scan will not work.
• Real-Time Network File Scan is unable to detect any file operations on the remote side. For example, if a file copy operation is totally completed on the remote side, the local Real-Time Network File Scan will not be aware of it.

The network file scan feature was created some time ago, so it is out-of-date. The current security policy is every machine needs to install AV. A machine without an AV installed is not allowed because it's at a very high security risk.

Since Network File Scan may not detect malware files and every machine should install AV, it's not necessary to enable it becuase it may cause confusion when a malware file in the remote side is not detected by Network File Scan.