In Gym env, get pybullet.error: Cannot load soft body. & Cannot load URDF file.(deformable)

[aganganga]

I am trying do RL with deformable objects in pybullet. I first try to the code of "kukaGymEnv.py" by sample code in pybullet_env.

I replaced the robotics arm's target "self.blockUid" from a rigid object block.urdf,
to other rigid objects is good, but to a deformable one torus_deform.urdf get the trouble.

I could run loadURDF call torus_deform.urdf well in pybullet general codes, only get the "pybullet.error:Cannot load URDF " file while run the spinning up RL training.
I use loadSoftBody to call other deformable objects faced the same problem. They are usually fine, only when run the spinning up RL training get the error.

I want to know what is the difference between the use of deformable objects in this environment and the general rigid body?
Or is it that deformable objects cannot exist in this environment?

Thanks for answering.