This is due to having the feed due to your microphone feed coming in along with your console feed via the Game Source layer. If the Game Source layer is removed from the stage in Lightstream Studio, this will result in the mic audio that was also being brought in to not be heard as a result.
In cases like this, you can have add a microphone and camera to your stage when you're not wanted to show gameplay so that you can still chat with your community in a chatting format. Please note that in this particular example, it would be recommended to hid the camera and mic on your computer when bringing your console feed back onto the scene to help avoid an echo in your stream due to two microphones being on the stage. The article shared here covers some helpful info to keep in mind if you do notice an echo on your stream!