External editors don't update files remotely

Since v5.5.0 (Build 3839), editing with an external editor won't update file on remote server. I've tried with gVim and Notepad++ and the issue is the same. When updating a file with WinSCP internal editor, file is updated remotely.
I've tried protocols SFTP and SCP and it is the same problem.

When I enable session log, I can see that WinSCP is doing some operations when I'm saving my file with internal editor while I don't see any operations when I'm doing the same thing with an external editor.

All was ok with previous version of WinSCP.
My version of Windows is 8.1 64 bits.

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.

I attach two trace files : one when using internal editor and the other when using external editor (gVim).

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