And MARS is the issue. With only ARFoundation, ARKit, ARCore, and XR Plugin Management I can build to the iPhone just fine. But *as soon* as I install the MARS package provided by unity and then try to build to my iPhone via Xcode, the app crashes with the above error. Using Unity 2022.3.5, ARFoundation 5.0.6, ARKit 5.0.6, ARCore 5.0.6, MARS 1.5.0, and Xcode 15.0 beta 4. And yes, I have to use the beta because my iPhone has iOS 16.5.1, but the most recent non-beta Xcode doesn't support that version. Thanks, Crapintosh.