I have a user (Windows 7, Acrobat Standard 10.1.8) who is unable to see files when trying to open files from within Acrobat or insert files to an existing PDF document. If they go to the file outside of Acrobat they can open the file. If they open Acrobat first and then go to File > Open no files show up in the window. Same for inserting files. If they try to insert a PDF into an existing PDF the window shows no files, no matter if PDF files or All Files are selected.
I uninstalled and reinstalled Acrobat and that corrected the problem for a day. I have installed all updates so not sure what the problem is.