I'll try to attach the WinSCP log file. In case I can't, the log file repeats the same 4 lines over 5000 times and then suddenly ends. Apparently, the server is reporting "" as the current working directory for this user.
> (timestamp) PWD
< (timestamp) 257 ""
. (timestamp) Got reply 1 to the command 16
. (timestamp) Getting current directory name.