I had the same scenario. I read the readme.txt file located in C:\SWSETUP\sp78717 and noticed that Device manager was showing that the correct Drivers for the HD Graphics 530 (under Display adapters) was actually installed (Driver Version: 188.8.131.5251). I still see sp78717 listed in the HP Support Assistant as needing another install.
The same thing is also happening to me on a HP ProDesk 600 G2. Device Manager shows Intel HD Graphics 530 Driver Version: 184.108.40.20651 is installed. But HP Support Assistant keeps wanting to install. A little annoying!