Invalid access to memory - TCustomScpExplorerForm::RemoteTransferFiles

<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 5.17.7

Error message:
Invalid access to memory.

Stack trace:
(00F880A6) __DynamicCastVCLptr
(00F8862A) C5296_3
(00F8A692) ____ExceptionHandler
(00F8744C) __ExceptionHandler
(00087C8F) ntdll.dll
(00073131) ntdll.dll.KiUserExceptionDispatcher
(00016B48) TCustomScpExplorerForm::RemoteTransferFiles
(00010918) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(000441B5) TNonVisualDataModule::ExplorerActionsExecute
(003E85CC) System::Actions::TContainedActionList::ExecuteAction
(001C71B5) Vcl::Actnlist::TCustomAction::Execute
(003A4BA8) System::Classes::_18201
(000438E9) USER32.dll
(00025137) USER32.dll
(00024289) USER32.dll
(0002406B) USER32.dll.DispatchMessageW

(00F88C95) C5296_3
(00F8A26F) _ReThrowException
(00016C1C) TCustomScpExplorerForm::RemoteTransferFiles
(00010918) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(000441B5) TNonVisualDataModule::ExplorerActionsExecute
(003E85CC) System::Actions::TContainedActionList::ExecuteAction
(001C71B5) Vcl::Actnlist::TCustomAction::Execute
(003A4BA8) System::Classes::_18201
(000438E9) USER32.dll
(00025137) USER32.dll
(00024289) USER32.dll
(0002406B) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.

<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 5.19.5

Error message:
Invalid access to memory.

Stack trace:
(00FC3EFE) __DynamicCastVCLptr
(00FC4482) C5294_3
(00FC64EA) ____ExceptionHandler
(00FC32A4) __ExceptionHandler
(00088F2F) ntdll.dll
(000743C1) ntdll.dll.KiUserExceptionDispatcher
(00017078) TCustomScpExplorerForm::RemoteTransferFiles
(00010D70) TCustomScpExplorerForm::ExecuteFileOperation
(00010E91) TCustomScpExplorerForm::ExecuteFileOperation
(00010F17) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004706E) TNonVisualDataModule::ExplorerActionsExecute
(0040B564) System::Actions::TContainedActionList::ExecuteAction
(001CD651) Vcl::Actnlist::TCustomAction::Execute
(003C7B64) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000233F9) USER32.dll
(000231DB) USER32.dll.DispatchMessageW

(00FC4AED) C5294_3
(00FC60C7) _ReThrowException
(0001714C) TCustomScpExplorerForm::RemoteTransferFiles
(00010D70) TCustomScpExplorerForm::ExecuteFileOperation
(00010E91) TCustomScpExplorerForm::ExecuteFileOperation
(00010F17) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004706E) TNonVisualDataModule::ExplorerActionsExecute
(0040B564) System::Actions::TContainedActionList::ExecuteAction
(001CD651) Vcl::Actnlist::TCustomAction::Execute
(003C7B64) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000233F9) USER32.dll
(000231DB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.