I had similar problem when first setting up the 8500.
Had to do factory reset, then the setup asst appeared again.
PAGE 294 IN THE PDF MANUAL
I also unplugged all of the HDMI cables from the receiver and TV before resetting and then plugged them back in because, as I recall, when I first did the factory reset it didn't work. No idea why this worked, could've been a loose cable. Also now recall that I had my satellite receiver plugged in to the aVR , possibly turned on. So suggest only connecting the TV to the aVR and not to and the other components when you do the initial set up based upon my experience in connecting my AVR.