[Bug] Legs and Feet of avatar twisted in HumanBodyTracking3D

[aliameenrana]

Unity bug report case number
Please log a bug at https://unity3d.com/unity/qa/bug-reporting and post the case number here.

CASE IN-81937

Describe the bug
In HumanBodyTracking3D scene, the legs and feet of the robot are twisted when running 3D pose tracking. This problem is present on iPhone 12 Pro Max running iOS18. Not present on iPhone XR running iOS17.5

The issue is present on all ARFoundationSamples and all ARFoundation package versions so most likely an issue with ARKit inputs that ARFoundation uses.

A

This user suggested reverting to 5.1.0-pre4 but that does not work either.

To Reproduce
Steps to reproduce the behavior:
Clone ARFoundationSamples repository, build the app and run on an iOS device running iOS18. Go to HumanBodyTracking3D scene, have someone go in front of the back facing camera and see the feet are pointing downward. The legs are also twisted but that becomes obvious once you try to run it using your own character and is not very obvious when running it with the Apple ARKit robot.

Expected behavior
The robot's legs and feet should mirror the legs and feet of the actor.

Actual behavior
The robot's legs are twisted and feet point downward

Smartphone (please complete the following information):

• Device: iPhone 12 Pro Max
• OS: iOS18
• Unity version: Unity 2022.3.14f1, Unity 6.000
• ARFoundation version: 5.1.0, 5.1.5, 6.0, 4.2