I am experiencing the same issue via Unity's ARKit Face Tracking package, Version 3.1.7 - October 20, 2020. I see this behavior in the float values of the blendshapes, as well as in the default blendshape animation example: The 3D face asset is clearly raising both brows when I raise my Left brow. Is this a known bug? If so, is there an ETA? Thank you.

I had the same issue when building from Unity (a new visionOS project from scratch in XCode worked just fine, I would recommend sanity-checking this first). The solution that worked for me was to update the Player Settings in Unity like so: “Player > Other Settings > Configuration > Target SDK > Simulation” If you then Build your project and open in XCode, you should see the Vision Pro simulator populate in the "Run Destinations" dropdown menu.