americanaudiophile :
I think the problem is that you are running 6 channels in the main zone. The receiver only has 7 channels and you need two for the zone 2 output. That why it switches both zones to music.
You will need to back down to 5.0 in the main zone or add an amplifier to drive the remote speakers. You may need to use the zone 3 line level outputs for the amp.
So, this is how the speakers are configured:
Front A: Front R and Front L Speakers
Center: Front Center Speaker
Surround/Zone 3: Surround R and Surround L Speakers
Surround Back/Bi-Amp/Front High/Front B: Rear Center Surround Speaker (connected to L per manual)
Zone 2: Outdoor Speakers
The instruction manual says, "You can only enable the SPEAKERS ZONE 2 terminals if you set [SURROUND BACK/ZONE 2 Priority] in (Speaker Settings) to [ZONE 2 Terminals], and turn on the ZONE 2 power."
My understanding is that when you turn on ZONE 2 and select ZONE 2 as the Priority, it automatically turns off the Surround Back Speakers. If this is correct, and the Surround Back Speakers are turned off, then it will still exceed the number of speakers being used?