Re: !S
It should work even if you configure the path in GUI in advance. Can you post an example of your previous script?
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Bug reports without an attached log file are usually useless.
C:\log\WinSCP-!S-!Y-!M-!D-!T.xml
WinSCP-test-2013-08-20-074500.xml
WinSCP-test-2013-08-20-074700.xml