Reproduction steps:
1. Open the attached “AnimationRigRepro.zip” project
2. Open the “SampleScene” scene
3. Select “Woman” Prefab in the Project Window (3D_Assets > Avatar > Meshes)
4. In the Inspector navigate to the “Rig” tab
5. In the “Animation Type” property dropdown select the “Generic” option
6. For the “Avatar Definition” property select “Create From This Model”
7. Press Apply
8. Enter the Play mode and observe the Game view

Expected result: The two-bone IK does not offset and remains the same as before entering the Play mode
Actual result: The two-bone IK gets offset

Reproducible with: 1.2.1 (2021.3.37f1, 2022.3.24f1), 1.3.0 (2022.3.24f1, 2023.2.19f1, 6000.0.0b15)

Reproducible on: Windows 11
Not reproducible on: No other environment tested

Note:
- Does not reproduce when the “Avatar Definition” is set to “No Avatar” or when “Animation Type” is set to Legacy