I have the same problem. I rely on PDF Tools to scan documents every day in my work.
I wasted precious time in a meeting with a client trying repeatedly to scan a document she had brought.
Later I remembered I still had PDF Tools 4 on my computer, which works—thank God! I depend on your software to scan documents in my work every day.
I, too, use WIA, and my computer runs Windows 7 x64.
Hope you fix this soon. Am so sorry I ran the updater today!