Hip Pinning not working with custom Avatar (Avatarsdk) - Knees and feet are floating

Hello 

(I am using a translation tool, so I apologize if any of my wording is strange. Please see the attached screenshot of my Inspector settings.)

I am trying to implement the Hip Pinning feature from the Movement SDK in my own scene, using a custom avatar.

What I am doing:

I am using the official Meta Movement SDK Hip Pinning sample scene (MovementHipPinning) as a reference. (Reference: https://developers.meta.com/horizon/documentation/unity/movement-advanced-samples )

I am using a custom avatar created with Avatarsdk (metaperson.avatarsdk.com), which uses a standard Unity Humanoid rig. (Avatar Source: https://metaperson.avatarsdk.com/ )

I have set up the Character Retargeter on my custom avatar and added a Target Processor Container for Hip Pinning, similar to the sample.

The Problem: In the official sample scene, the avatar sits perfectly, and the knees are correctly positioned.

However, with my custom avatar, when Hip Pinning activates:

The knees bend at a strange angle. (They point in the wrong direction.)

The knees are floating (not in a natural sitting position).

The feet are also floating and do not touch the Target Foot locations.

What I have tried: I believe this problem is related to the Transform coordinates set in the Target Processor Container (specifically the Target Foot and Target Hint objects).

I have spent a lot of time adjusting the positions of these Transform objects (moving the Target Hint further away, changing the Target Foot position, etc.), but I cannot get the avatar to sit correctly.

My Goal: My goal is the same as the sample scene: to have my custom avatar sit correctly on a chair, while still allowing the upper body (head and hands) to move freely.

My Questions:

How should I correctly position the Target Foot and Target Hint transforms for a custom avatar? Are there specific rules for placement based on the avatar's proportions?

Are there any other settings within the Character Retargeter that I need to check when using a custom (non-Meta) humanoid avatar for Hip Pinning?

Thank you for any help you can provide.