Audio not playing in multiple Theaters at the same time

Theater playback is complex as it is necessary to decode or upmix audio signals to provide an Immersive Audio experience with a lot of channels. As of today, the ISP is not able to decode or upmix two different Theaters simultaneously. You can configure multiple Theaters and child Theaters to fit your needs, but not use them at the same time. On the other hand, you can create Audio Zones that can actually play along with your main Theater.