Can't load URDF

Hi,

I’m using Isaac Sim with ROS2 Humble (Ubuntu 22.04) and set it up following these instructions.
I’m trying to import a URDF from this Diablo GitHub here, using the URDF Importer extension described in this tutorial, but when I import it, the visuals don’t show up (see picture below):

On the terminal where I launched Isaac Sim, I get the errors:

[765.534s] [ext: omni.kit.registry.nucleus-0.0.0] startup
2024-03-27 17:29:09 [765,828ms] [Warning] [carb] Client omni.ui has acquired [omni::ui::IGlyphManager v1.0] 100 times. Consider accessing this interface with carb::getCachedInterface() (Performance warning)
2024-03-27 17:48:33 [1,930,187ms] [Warning] [omni.usd] Coding Error: in _Get at line 3003 of /buildAgent/work/ac88d7d902b57417/USD/pxr/usdImaging/usdImaging/delegate.cpp -- Failed verification: ' prim '

2024-03-27 17:48:48 [1,945,219ms] [Warning] [omni.importer.urdf] ROS_PACKAGE_PATH not defined, will skip checking ROS packages
2024-03-27 17:48:48 [1,945,219ms] [Warning] [omni.importer.urdf] Path: file://$(find diablo_simulation)/meshes/base_link.stl not found
2024-03-27 17:48:48 [1,945,219ms] [Warning] [omni.importer.urdf] Failed to resolve mesh 'file://$(find diablo_simulation)/meshes/base_link.stl'
2024-03-27 17:48:48 [1,945,219ms] [Warning] [omni.importer.urdf] Prim /diablo_simulation/base_link/visuals not created
2024-03-27 17:48:48 [1,945,219ms] [Warning] [omni.importer.urdf] ROS_PACKAGE_PATH not defined, will skip checking ROS packages
2024-03-27 17:48:48 [1,945,219ms] [Warning] [omni.importer.urdf] Path: file://$(find diablo_simulation)/meshes/base_link.stl not found
2024-03-27 17:48:48 [1,945,219ms] [Warning] [omni.importer.urdf] Failed to resolve mesh 'file://$(find diablo_simulation)/meshes/base_link.stl'
2024-03-27 17:48:48 [1,945,219ms] [Warning] [omni.importer.urdf] Prim /diablo_simulation/base_link/collisions not created
2024-03-27 17:48:49 [1,945,222ms] [Warning] [omni.importer.urdf] ROS_PACKAGE_PATH not defined, will skip checking ROS packages
....

Before launching Isaac Sim from the terminal, I ran:

FASTRTPS_DEFAULT_PROFILES_FILE=/home/..../Dev/IsaacSim-ros_workspaces/humble_ws/fastdds.xml
source /opt/ros/humble/setup.bash
source /home/..../Dev/colcon_ws/install/local_setup.bash

I’m able to import a different URDF from the same colcon workspace that I’m using for the Diablo git repository. Would you guys have any ideas for what I can look into? Thanks in advance