Can an app detect the change from roomscale to stationary?

Hello all!

I'm developing a roomscale game for Quest 2 in Unity using the XR toolkit.  It needs the device to be in roomscale mode with a big enough play area inside the boundary.  I want it to display an error message to the user if they start it in stationary mode or switch to stationary during play.

I've been using the boundaryChanged callback of xrInput (an instance of XRInputSubsystem) to track changes in the boundary polygon, and that works fine.  But, to my surprise, the callback is not invoked when switching modes.  I tried polling xrInput.GetTrackingOriginMode() every frame but it always returns Floor regardless.

So, is it even possible to detect whether it's in roomscale vs. stationary, and if so, how?