Can't use particle_state_tensor in FleX

I want to use a function that obtains the centroid of a soft object among the modules provided by DefGraspSim.
The function requires particle_state_tensor, and I tried to update it. However, the error ***Can’t create empty tensor appears. There was a problem entering refresh_particle_state_tensor(sim).
Why does this error occur? How else can I fix it?