I was just looking thru the manual. First thing let's go thru the troubleshooting thing and are you using zone B or 2?
ZONE B function❏Cannot output audio to ZONE B •
To output audio to ZONE B, set the audio output destination to "ZONE A+B" or "ZONE B". ( p75)
Multi-zone function❏
Cannot ZONE-output the audio of externally connected AV components•
To output audio from an externally connected AV component to ZONE 2, connect it to any of HDMI IN1 to IN3 jacks. If the AV component is not equipped with an HDMI jack, use a digital coaxial cable, digital optical cable or analog audio cable. Also, the audio from externally connected AV components can be output to ZONE 2 only when the audio is analog or 2ch PCM signal. When the AV component is connected to this unit with an HDMI cable, digital coaxial cable or digital optical cable, change the audio output of the AV component to the PCM output. • When video and audio via HDMI input are output to ZONE 2, set "Input/Output Assign" - "TV Out / OSD" - "Zone 2 HDMI" ( p101) to "Use" on the System Setup menu.❏Others• If the audio signal is from the NET or USB input selector, zone output is not possible for DSD audio signals