"Visual tracking is lost" in tutorial

hi,
I was going through the Isaac ROS Vslam tutorial with Isaac Sim.
https://nvidia-isaac-ros.github.io/concepts/visual_slam/cuvslam/tutorial_isaac_sim.html

However, as soon as I launched isaac_ros_visual_slam, "visual tracking is lost" error kept on popping.
I tried echoing the topics published by visual_slam_node, but none of the topics published anything.
I looked at the image_raw topic published by Isaac Sim through rviz2 and it was just fine.

this is the error message printed.

What could be the problem?

By the way, I am using Ubuntu22.04 and ROS2 humble. I am running both Isaac Sim and Isaac ROS in a separate docker container. I am running Isaac Sim by run headless mode with streaming client. I followed exactly the document "development environment setup" and "isaac ROS Vslam quickstart" and installed isaac_ros_common and isaac_ros_visual_slam in the process.
Also, a strange point is, I tried Isaac ROS map localization and it worked.