Your problem may be related to a similar one I had. Contary to my expectations, Echo mode does not make an exact copy of the files on the left into the folders on the right. If SyncToy detects that a file on the right is newer than the one on the left it
does not overwrite it at all. You get no message about this. So as a backup tool, Echo mode is seriously flawed. You may end up with different file versions on the left and right sides and no obvious warning.
This applies to files. It may also apply to folders. Check the folder creation date and try removiing the right folder completely to see if that fixes it. Or copying your folder may be blocked by one of the various filter options.
Elsewhere on this forum Microsoft say they have abandoned further development of this software. You may have to try another tool.
