Drag & Drop between two servers fails

Hello,
sorry, my english is not very whell, but i hope you understand me :-)
i'am using winscp to copy files between two servers.
server A is connected via ftp, server B via ssh.
drag & drop setting is "use temp-dir". winscp runs in two windows (explorer-mode).
now, i drag & drop files (and directories) from server A to server B. winscp starts to download all files into the temp-folder. after download is finished, winscp begins to copy the files to server B. the problem is, winscp delete the temp-folder automatically befor copyed all files to server B. all settings i tested have no effect. how can i disable temp-folder-auto-delete?
great thanks for help!

Why do you think it's WinSCP that deletes the files?
Isn't it some other process that does that?
Did you try configuring WinSCP to use a custom folder for temporary files, instead of the system temporary folder?
https://winscp.net/eng/docs/ui_pref_storage

No other prozess ist running that does that.
I configuring WinSCP to use custom folder for temporary files.
If i watch the prozess and i close the WinSCP-sourcewindow after downloading to tempfolder is finished (in right moment), the files keep in the tempfolder and WinSCP-destinationwindow can copy all files to server B. WinSCP deletes the files, i think so. If i leaf the sourcewindow open, the files will be deleted and the prozess fails.

Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.