isaaclab gets stuck while loading the USD file output by 3dgrut.

[YongcanZhou]

I modified the usd file in isaaclab to be a 3dgrut exported file, but it got stuck.
https://github.com/isaac-sim/IsaacLab/blob/main/source/isaaclab_tasks/isaaclab_tasks/manager_based/manipulation/stack/stack_env_cfg.py#L44

This is the log from the original execution of isaacsim (work right):
kit_20251203_091302.log

This is the log in isaacsim after the file was replaced(work stuck).
kit_20251203_091111.log

Thank you so much!

[ntrlmt]

We were able to reproduce a similar freezing issue when importing 3DGS-generated USD files into Isaac Lab, and it turned out to be a version compatibility problem between Isaac Sim and Isaac Lab.

In our environment, 3DGS USD files can be opened correctly with Isaac Sim 5.0 or later when using Isaac Sim alone. However, when using the combination of Isaac Sim 5.0 and Isaac Lab 2.2.1, Isaac Lab freezes during USD loading (the GUI becomes unresponsive without clear error logs).

After upgrading to Isaac Sim 5.1 together with Isaac Lab 2.3.1, the same USD files could be imported without any issues.

Summary of our findings:

• Isaac Sim 5.0 alone: works
• Isaac Sim 5.0 + Isaac Lab 2.2.1: freezes during USD import
• Isaac Sim 5.1 + Isaac Lab 2.3.1: works

If you encounter freezing when loading 3DGS USD files in Isaac Lab, we recommend upgrading both Isaac Sim and Isaac Lab to the latest compatible versions (at least Isaac Sim 5.1 and Isaac Lab 2.3.1).