I have two identical Windows 10 computers, each with Adobe Acrobat Reader DC (2017 Release, Version 2017.012.200978) on a network. If I copy a PDF file from one computer, say “A”, to a shared folder on the other, say “B”, and then edit the file on “B” from Adobe Acrobat Reader DC on “B” e.g. add a comment, the PDF file then becomes invisible to “A” i.e. “A” can see all the other files in the folder except the edited PDF file. Further, if one then attempts to copy the same PDF file to the same folder on “B” thereafter, the is an error message that “A” does not have permission to paste the file. “A” can only paste the PDF file again to the folder in “B” if “B” deletes the edited file first.