10x. I was only looking at the mask hints and couldn't find this info there. Perhaps it is important enough to add a single line for directories.

To filter directories, you have to explicitly use a directory mask (by appending a slash).
https://winscp.net/eng/docs/file_mask#directory

I have a directory of directories. I set the filter properly, but I still see all directories.
It seems the Filter only works for files. Please, alter it so it filters directories too!