ARFoundation 4.1: No Face Subsystems detected

I am using this code in ARFoundation 4.0.6 to detect if face detection is possible:

Code (CSharp):

1.  
2. var descriptors = new List<XRFaceSubsystemDescriptor>();
3. SubsystemManager.GetSubsystemDescriptors(descriptors);
4. if (descriptors.Any()) _faceTrackingDescriptor = descriptors.First();
5.  

This works fine on my iPhone X.

But since I upgraded all ARFoundation packages to 4.1, no face tracking descriptors can be found anymore. The list is empty.

What might be the reason for this? I cannot find any changes regarding face tracking in the change logs.

 

I am curious if this is the same issue we are experiencing?
https://forum.unity.com/threads/ios-auto-build-ar-facetracking-issue.970806/

 

No, doesn't seem to be the same thing.

I just came back to this thread because I finally *have* to upgrade to 4.1.x, because a severe iOS 16 camera bug.

And ran into the same issue I already reported back in 2020...

 

I just found out what the root cause is: The newer ARKit package adds a new option to the ARKit project settings: "Face Tracking". This has not been enabled by default. After I ticket the box, the descriptor becomes available.