Thanks for your note, it's the closest I've seen to a fix for my identical problem. But I can't get it to work.
Can you give more details on your Step 3, "install the "HP Universal Print Driver for Windows PCL6 (64-bit)." ? When I run the install, it gives me three choices for Installation Mode -- Traditional, Dynamic, and USB Plug-n-Play. None of them seem to be able to keep that darn "PNP SCAN NULL" driver from re-appearing, and the scanner still doesn't work.