Thanks GreatMarko for responding. I'm assuming that the soft, hard, and symbolic links issue resides with the use of the Windows Libraries. To help correct the issue, I've tried deleting all affected folders from Sync on all machines, removing all folders from the libraries, and then adding the folders back into Sync. I don't believe there are any other kinds of linkages in any of the folders. I'm not sure if it matters, but as these were long established folders, I've used the secrets to reestablish the connections.
Anyway, the problem hasn't gone away. As soon as I started things up again, I kept getting notifications about illegal characters, and how Sync was renaming the files it was transferring. In one folder I had over 25000 duplicated files in a folder that originally housed about 20; all generated in a very short period. Some of the files are problematic to remove, as the files names are so long (.Conflict .Conflict .Conflict .Conflict .Conflict...) that Windows can't remove them.
The odd thing is that the issue only affects a limited number of sub-folders, and then not all of the files in those folders. The issue is confined digital images produced by two of my cameras and no others. The file names are as they were named in the cameras, so they shouldn't contain illegal characters.
I've been using Sync for about 2 years and never seen this problem before. The files affected are not new, some are over 18 months old. I've been running Windows 10 on these machines since it became available. The problem surfaced about a month ago in a small way, but is now out of control. I've disabled Sync for now.
Any help with this would be most appreciated. Otherwise I think I'm going to have uninstall Sync and look for something else.