Don't know if this will help you or not.....I am using Adobe XI, and during the last update 11.6 to 11.8 I could no longer see previous pdf files, I played with the "Preferences" under "Edit" and discovered that under "Page Display"/Page Content and Information : Default Transparency Blending Color Space:" [options] 1. Working CMYK 2. Working RGB..............when I had Working CMYK I didn't see of my pdfs the page was blank...............changed to Working RGB and now I see all my PDF's.
Hope this works for you...............