Does the Onkyo receiver support sufficient HDMI bandwidth to handle 4k(60?) HDR? If so, you may need to go through the projector's menus to find options to enable 4k HDR / 4k60. I recently bought a 4k TV for use as a secondary monitor and it took me a while to figure out why it was only giving me 4k30 without HDR. Had to dig through the TV's passable UI to find the input configuration page and enable HDMI 2.0 on a per-port basis.