When opening a second file, it is displayed as Deleted.. (cannot be saved)

I've been having a problem with WinSCP for some time now: When I open a file, I can edit it normally and even save it. However, when I open another one, it is crossed out in red after a short time and marked as deleted.

I use it for a FiveM SFTP server. I use VS Code as the editor.

Make sure you do NOT have External editor opens each file in separate window (process) enabled:
https://winscp.net/eng/docs/ui_editor_preferences