Yes you missed that I hovered indeed the field and it was not highlighted. Sometimes it will highlight sometimes not.
Full row select is a good catch! I have enabled it. But it's not about the root issue, which stays the same.
Now I have a clue what's going on, also by testing the other ticket with the tab color. The drag-hover does not color the hover area, I think it's because the same Windows bug that does not color the tab title..

What is the technology you use for tab coloring? Or content coloring? "Microsoft’s Fluent design"?

I believe the "precondition" is clear. You have to drop to the Name column (i.e. when the folder name is highlighted), if you want to drop into the folder. Otherwise the files are dropped to the current working directory. Or did I miss something in your video?

If you do not like this behaviour, you can enable Full row select:
https://winscp.net/eng/docs/ui_pref_panels

This is tricky. Depends on the dark mode and how you move the mouse. Took some time to find how to reproduce.
Dragging by some specific path and having some unknown precondition it will not highlight the destination and the user does not "feel" the package was dropped in wrong place

@mregister: Please post a screencast.

Hello mregister,

That destination is consistent with the drop landing on folder 17. WinSCP documents that dropping onto a folder icon uploads inside that folder.

For a full list with no empty space, this avoids the ambiguous drop target:

• Select folder 100 in Windows File Explorer and press Ctrl+C.
  
• In WinSCP, navigate to /path/.
  
• Use Files > Paste (Ctrl+V). The default destination is the current remote directory.
  
• Check that the transfer dialog's destination is /path/ before confirming.
  

You can also drop onto the intended /path/ folder in the directory tree. If the confirmation dialog is hidden, enable Transferring of files in Preferences > Environment > Confirmations. Drag-and-drop confirmations have a separate option there too.

Official instructions:
https://winscp.net/eng/docs/task_upload
https://winscp.net/eng/docs/ui_pref_environment

AI-generated reply, checked against the documentation; not affiliated with WinSCP.

WinSCP displaying a long list of folders. Window is full. E.g. Folders are in /path/ as 1,2,3,4,5,6,7,8,9.....99
On left the tree is displayed
On right frame the folders 1,2,3,4...99
From Windows drag drop a new folder 100 to the frame
I am expecting to drop it to /path, instead it drops it at a random place like /path/17/100