Hi,
I found a fix for this issue. You need to reset all the speakers and start the set up process all over again. When choosing a layout, set up the surround sound speakers behind you and the soundbar in front of you. If you choose this layout during the setup, then the sound will play out of all speakers!
If you have all three speakers set up in front of you, they won't play all at the same time (only the two surround sound speakers). This is because the quality of the sound would be awful with all three playing at once when they are set up in front of you.