Polk Audio MagniFi MAX SR chromecast

When connecting to Polk Soundbar via Chromecast, surround speakers are not playing.
They turn on only when selecting music mode.

The problem, is that before Chromecast start playing, there was full 5.1 system, but after - only soundbar & subwoofer works.

Is it possible to make firmware update, witch will fix that problem?
I want to full 5.1 work always, no matter on source of music changed.