samba - Apr 2015 - win7 access centos samba folder, can only found one folder named unsysnc_discard

Hi

I have a centos 7 samba server. The config for /etc/samba/smb.conf is like below

[global]
    workgroup = WORKGROUP
    server string = Samba Server Version %v
    hosts allow = 127. 192.168.1.
    log file = /var/log/samba/log.%m
    max log size = 50
        security = user
        passdb backend = tdbsam
        load printers = yes
        cups options = raw
 [s3ql]
    path = /var/share/samba
    writable = yes


When I accessing the shared folder from other computer (linux) it is fine. I can
see the content in the folder.
When I accessing the shared folder from other compuer (win7 ) it is wired.
Nothing in the shared folder except an empty directory named
"unsysnc_discard".


Can any one help to explain?
This is not happening all the time. Only occasionally.