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 5.6.3
Error message:
Out of memory
Stack trace:
[011918C2]
[011918C2]
[0111E7EB]
[00FBB7BC]
[00FF6F55]
[00FFBA99]
[00FB683C]
[01560D29] @@Synchronizeprogress@Finalize
[00FF6B90]
[00FC19F3]
[0111F9BC]
[755962F7] USER32.dll
[75596D35] USER32.dll
[75596DE3] USER32.dll
[75596E41] USER32.dll
[77A80107] ntdll.dll.KiUserCallbackDispatcher
[755996C0] USER32.dll.SendMessageW
[00FF1D9C]
[00FBB4BA]
[00FBB538]