I have issue using Explorer interface and drag'n drop from server.
Using "shell extensions" option, WinSCP create a temporary /scp* folder and next show modal window:
"WinSCP does not manage to identify where the file has been transfered"
I can drag'n drop files using "temp dir" option.
Using Commander Interface, I notice WinSCP is trying to use an old network drive.
Maybe Explorer Interface is trying to use this same old drive...
Windows 10 Pro 1803