I'm not really sure if this is the best place to ask but we're experiencing a very odd issue which started around a month ago and I can't find a support link to contact Adobe directly.
We deploy Adobe Reader to our client PCs using the 2017 Classic track, currently patched to 17.011.30138 (latest available).
We've had roughly 20 users report to us that their PDF files (hosted on network shares) are disappearing when they try to open them. I'm not sure where to start looking on this one. I can't find anything related to this in Microsoft support forums and it only seems to be PDF files that are affected. This occurs on multiple file shares and across Windows 7 and 10. The only constant seems to be Adobe Reader.
I've seen someone else has posted the same issue over on Microsoft's Technet, apparently deleting the copy of the file (which is copied to AppData\Local\Temp) the issue is resolved for that particular file.
Could really do with some Adobe support on this one!
Just to further update, I can now replicate this issue. If I open a PDF from an email, the PDF is saved into the Temp folder, if I then save the PDF somewhere on the network (keeping the same name), open and close it the file is deleted. If I clear out the Temp folder of PDFs the file remains.