[Question] Title: Error "body relationship points to a non existent prim, joint will not be created" near end of RL training

[Fuhua-Bot]

I'm encountering an issue during the RL training process while using the IsaacLab environment for my custom robot. I have created a custom manager-based RL environment and set up the necessary MDP components for my robot. However, near the end of the training process, typically around iteration 148/150 or 149/150, the following error appears:

body relationship /World/envs/env_0/Robot/BipedalWheeledRobot/drive_link_03 points to a non existent prim, joint will not be created

Once this error occurs, the learning process halts and the environment crashes. Although this issue usually arises very close to the end of the training cycle and may not significantly affect the overall process, I'm curious about the cause and whether it indicates a deeper problem.

Environment:

IsaacSim version: 4.1.0
Operating System: Ubuntu 22.04
GPU: 3090Ti and A5000 Ada

This issue happens consistently during the last few iterations of the training process and may relate to how the environment or robot's joints are being set up. While the issue does not seem to severely affect overall learning, I would appreciate any insights on its root cause or possible fixes.

Thank you for your help!