Thanks for your report.
I have sent you an email with a debug version of WinSCP to address you have used to register on this forum.
<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>
WinSCP 5.6.4
Error message:
List index out of bounds (0)
Stack trace:
[00722F75] System::Classes::TList::Get
[00722F75] System::Classes::TList::Get
[007D942A] Customdirview::TCustomDirView::DDProcessDropped
[007FEF27] Dragdrop::TDragDrop::WndMethod
[0073FFF8] System::Classes::_18201
(000A44E8) user32.dll.[7E9F54E8]
(000A4C21) user32.dll.[7E9F5C21]
(000A737E) user32.dll.[7E9F837E]
(00068420) user32.dll.[7E9B9420]