Help with Allegro fingertip reaching using refsite

[Tadinu]

Intro

Hi, thank you very much for the holy work!
I am a PhD student and using MuJoCo for my research on hand manipulation control.

My setup

MuJoCo 3.2.7
Ubuntu 22.04

Hand model
Allegro

How to reproduce
In the attached packaged

• Run task.xml
• Red ball is a mocap body having a site as the refsite target
• Blue ball is the site at thumb endtip
• Note: refsite_mocap.xml is a modified version of refsite.xml, and it works as intended

My question

I'm trying to use refsite on a mocap body as the target for finger endtips, however it seems not to work for the thumb. I would be so grateful if you may lend a look?

Thanks a lot in advance!

Minimal model and/or code that explain my question

ALLEGRO_REFSITE_TEST.zip

Confirmations

• I searched the latest documentation thoroughly before posting.
• I searched previous Issues and Discussions, I am certain this has not been raised before.