Failed to fix the robot with a 'root_joint' when starting simulation

I’m editting a scene in IsaacSim. Before starting simulation, it looks in this way

But when i start the simulation, the panda just fly and lie on the table and dishwasher in a strange angle.

The panda has a ‘root_joint’, attached to the ‘robot_base’ of panda. In my understanding, it serves to fix the articulation.

I don’t know what is going wrong. I do need to fix the base of the robot in order to debug my manipulation task.

This is my usd file (663.3 KB)

I would appreciate any help.