SV510X-0806 Audio Output Issues

I have a Vizio Vizio SV510X-0806 and a Sony X90J TV. No matter how I configure it, there are times when the handshake at startup fails and the TV switches to TV speaker output.

I then have to pull out my TV remote and manually change the output to Audio System to get it to start playing through the speakers.

I’ve seen some say they have success with other models by turning off Auto Power Off mode or Eco Power mode, however I have no remote, there is no option in the Vizio app, and every physical button combo (Power + Vol Down for 5 seconds) does nothing but switch it to Demo Mode.

Am I out of luck, or is there any option for this to be fixed?