Apps cannot access the cameras on Vision Pro: https://developer.apple.com/videos/play/wwdc2023/10094/?time=588

It’s beta software, and so bugs should be expected. Your best course of action is to report the bug using Feedback Assistant: https://developer.apple.com/bug-reporting/

From that session: How accurately can the headset know a user's location? For a unit by itself, you should expect accuracy similar to that of a Mac, so that's about 100 meters... However, if your iPhone is nearby, this device can leverage existing connections between these two devices to improve the location accuracy you would get from the headset to be on the same level as that of an iPhone. So, although it's not said explicitly, it seems clear that Vision Pro does not literally have GPS.

Something to do with this feature, perhaps? Do you see the new "Wide" and "Ultra Wide" options in your menu bar? Control the composition of your video when using Studio Display or iPhone as your camera. Adjust the frame with zoom and pan controls or use Recenter to automatically place yourself in the center of the frame. From https://www.apple.com/macos/sonoma-preview/ .