Mixed reality (MR) environments provide great value in displaying 3D virtual content. Systems facilitating co-located multiuser MR (Co-MUMR) experiences allow multiple users to co-present in a shared immersive virtual environment with natural locomotion. They can be used to support a broad spectrum of applications such as immersive presentations, public exhibitions, psychological experiments, etc. However, based on our experiences in delivering Co-MUMR experiences in large architectures and our reflections, we noticed that the crucial challenge for hosts to ensure the visitors’ quality of experience is their lack of insight into the real-time information regarding visitor engagement, device performance, and system events. This work facilitates the display of such information by introducing immersive in situ visualizations.