TV is LG C9 which support eARC and has HDMI 2.1.
AV Receiver is Denon AVR-X3600H which supports eARC.
Infuse Pro 6.
MKV files via Plex that are TrueHD or DTS-HD MA are not passing through to the Denon. Tested with Apple TV 4K directly connected to the Denon and LG.
Denon displays the Source as Apple TV, Sound as Multi In + DSurround, and Signal as PCM.
What setting should I change?