Enable SFTP Logs
SFTP logs are disabled by default. Sometimes you need to enable the logs see what the users are upload/downloading from the server. You need to make two changes to enable SFTP logs.
Edit the subsystem line in /etc/sshd/sshd_config
Subsystem sftp /usr/libexec/openssh/sftp-server -f LOCAL7 -l INFO
Add below lines to /etc/sysctl.conf
#sftp logging local7.* /var/log/sftpd.log