Adhesion actuator 'gap' parameter not detecting inactive contacts.

[meeraranjan]

Intro

Hi!

I am a student and, I use MuJoCo for my research for manipulation.

My setup

Mujoco version: 3.9.0
Python version: 3.10.12

My question

I was trying to simulate a suction gripper on an arm using the Adhesion actuator. But I couldn't get any blue cylinders even though the gripper pad was very close to the object.
Tried to run the example (no modifications): https://github.com/google-deepmind/mujoco/blob/main/model/adhesion/active_adhesion.xml
While the winch sphere recognizes inactive contacts, the '4boxes' body doesn't show any blue contact cylinders. I can only see orange cylinders, when the gripper rectangle touches the box surface. Any help would be greatly appreciated!
Thank you!

Minimal model and/or code that explain my question

No response

Confirmations

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