Don’t replace owner/group when uploading files with WinSCP
WinSCP by default uses temporary file names for files above a certain size, when uploading to a server. This makes you lose permissions and user/group settings on files you upload and chose to replace existing files on the server.
You can disable this here by making it not use temporary files.
Feedback thread on the official forums: https://winscp.net/forum/viewtopic.php?t=45