Page 41 of the manual? Not sure if there is something in the setup menu you need to do as well. It does mention that HDMI control is not available in zone 2. Someone here who is way more knowledgeable than me can help I'm sure.
LG 65 EF 9500,Yamaha 3050,Oppo 203
Directv C61 4K box, Apple TV, SONOS Connect
Triad Bronze Center, Triad Bronze LR-H Atmos, Elan inwall surrounds, Velodyne Subs,
Savant Remote, Harmony Ultimate Home remote
"It ain't 4K if it ain't shot in 4K"