Isaac sim Assembling Robots

When isaac sim assembles Robots, my robotic arm flits and flits.
Similar errors occur at the same time:2024-08-22 11:49:42 [Warning] [omni.physx.plugin] Invalid PhysX transform detected for /World/firefighter/link1.
The robotic arm then returns to its original position and cannot be controlled at the same time.
Attached below is my urdf file, which includes the robot and a claw, my intention is to attach the left and right arms of the robot to the claw.
Desktop.zip (30.0 MB)