Meta XR Simulator only opens once, then breaks

I'm trying to use the Meta XR Simulator to test multiplayer in my mixed reality game using two instances of the Unity editor.

When enabling the simulator and clicking play for the first time, it starts correctly and I can move in the scene using my keyboard and mouse. After a moment (I think when I try clicking in the editor or another window), the simulator interface becomes unresponsive, but I can strangely still control the virtual rig as I see it move in the editor scene view.

Seeing this, I stop play mode and try to run it again, but despite the virtual room server seeming to launch correctly, the simulator itself doesn't open. No matter how many times I try to reset play mode, it no longer opens like the first time. Closing the editor and relaunching it is the only way to fix it but it sill breaks after the first time.

I don't want to restart the editor every time I need to go in play mode. Is there a solution for this?