Surround not working - only front speakers active

[simplenotezy]

I am trying to help an owner of a RX-V663. They have set up all their speakers, and it used to be working, but it is no longer working.

Only the front left and right speakers output volume. The center and rear left/right are not outputting any sound. I have tried going into "Test Tone" to figure out if speakers would output anything, but when I turn on "Test Tone" no sound is outputted at all. When I turn it off, the front speakers go back to playing sound. When Test Tone is active, I see it shuffles between all speaker icons on the display, but no sound is displayed. See image:

http://imgur.com/a/aJu9feE

I assume that the wiring is done correctly, since this has been working before, but just not anymore.

When I turn on the Receiver it displays "STRAIGHT" on the display. It is playing from a Chromecast via HDMI from a Panasonic TV.

What can I do to debug further? I have been playing around with the manual, but it's pretty confusing to say the least.

 

[MDK210]

I found the owners manual on Crutchfield, reset the entire system (pg. 119) then go from there. If the reset doesn't work unplug everything and connect one pair of speakers at a time as to identify any hardware issues.