Briefcase does not seem to "see" some PDF files

I have a home LAN with two PCs and two laptops connected. I often use a briefcase so I can work on various computers and still have the files stay current.

I recently set up a briefcase between the two PCs. It works fine, with one problem. One of the folders two levels down in the briefcase should have copied over several PDF files. It did not. They are on one computer, but not on the other.

The other folders that I checked that contain PDF files worked fine -- the files copied over. Just this one folder seems to be a problem.

The only unusual thing I can think of is that most of my PDF files were created using Acrobat. Recently, though, I have used a different free PDF editor. But the files are all PDF files.

In the past, I have had some trouble with briefcase and PDF files. Perhaps there is some underlying incompatibility there. Any help would be appreciated.

 

Turns out that the PDF files are in the folder, so Briefcase is working right. But for some reason, for this folder the PDF files cannot be seen. Tried to adjust the Folder Preferences, but could not find anything that affects that. There are no hidden folders, or anything like that.