Drag and Drop Upload in Explorer Interface is refused

WinSCP version 5.13.8172
Drag and Drop Upload is refused
Copy/Paste Upload is accepted

Where exactly do you drag the files from?

Tried from Windows Explorer and from desktop. both refused.
Also checked ftp-connection in FTP-server logfile. No errors or permission issues in Server logfile.
Copy/Paste no problem nor from desktop or WinExplorer.

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.

As you have found yourself, the cause of the problem is that you run WinSCP with elevated privileges ("as administrator")

It's a security measure. Windows does not allow you to drag files from non-elevated application to elevated one. It has nothing to do with WinSCP.