When I execute the code Session.ListDirectory, the only RemoteDirectoryInfo.File entry I find is "..", same shows in the WinSCP GUI. This is an older FTP server, but I can list and see fine even with built-in FTP application in Windows with command prompt.
My same methods and code works fine on 12 or so other FTP servers.
### Below is my output from the logs which shows the directory listing
. 2018-04-02 14:21:30.154 Directory listing successful
. 2018-04-02 14:21:40.481 Getting current directory name.
. 2018-04-02 14:21:40.481 Retrieving directory listing...
> 2018-04-02 14:21:40.482 TYPE A
< 2018-04-02 14:21:40.497 200 Command okay.
> 2018-04-02 14:21:40.508 PASV
< 2018-04-02 14:21:40.512 227 Entering Passive Mode (10,1,1,49,13,161)
> 2018-04-02 14:21:40.512 LIST -a
. 2018-04-02 14:21:40.512 Connecting to 10.1.1.49:3489 ...
< 2018-04-02 14:21:41.821 150 File status okay; about to open data connection.
. 2018-04-02 14:21:41.827 Data connection closed
. 2018-04-02 14:21:41.827 A180402000008AMA FIXED 2048 ********
. 2018-04-02 14:21:41.827 R150728070156AMA FIXED 2048 ********
. 2018-04-02 14:21:41.827 R150728121066AMA FIXED 2048 ********
. 2018-04-02 14:21:41.827 R151127074200AMA FIXED 2048 ********
. 2018-04-02 14:21:41.827 R141202092604AMA FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 DIRP_FILESEG FIXED 2048 ********
. 2018-04-02 14:21:41.827 P180327065442AMA FIXED 2048 ********
< 2018-04-02 14:21:41.961 226 Request successful. Closing data connection.
. 2018-04-02 14:21:41.961 Directory listing successful
. 2018-04-02 14:21:41.961 ..;D;0;1899-12-30T05:00:00.000Z;0;"" [0];"" [0];---------;0
. 2018-04-02 14:22:12.189 Sending dummy command to keep session alive.
> 2018-04-02 14:22:12.189 TYPE A
< 2018-04-02 14:22:12.189 200 Command okay.