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 5.6.5

Error message:
Invalid access to memory.

Stack trace:
[011163A3] Vcl::Forms::TCustomForm::IsFormSizeStored
[7742B466] ntdll.dll