Synchronization – File not saved via WinMerge comparison

Version:
WinSCP 6.3.2 on Windows 10 22H2
Protocol:
SFTP
Steps:

1. Synchronize (Direction: Remote)
   
2. Compare a file (external comparison tools: WinMerge)
   
3. Copy some changes from Local file to Remote file
   
4. Save Remote file
   

Expected:
Remote file saved with some changes from Local file.
Actual result:
Remote file not changed – as if nothing has happened.

Saving changes in WinMerge works when comparing files outside of the Synchronization checklist, e.g. in the explorer UI.

Indeed, the files are not saved. That's how it works.

So it seems synchronization, in the current implementation, is for file-level changes. For line-level changes, the explorer view is the way to go.

Perhaps "saving line-level changes in synchronization checklist" is worthy of an RFE? This would allow both file- and line-level changes in the same workflow.