Why dose the indenter penetrate the soft body?

I conducted a soft body deformation simulation experiment in Isaac gym, using an indenter to contact a soft body sphere from below, expecting the sphere to deform reasonably. However, the indenter directly penetrated through the soft body sphere. I was on the verge of collapse, not knowing what happened. Initially, I used position control for real-time control of the indenter, namely DOS_MOD_POS, but occasional penetration occurred. Later, I used DOS_MOD_POS and apply_actor_dof_efforts to control the force of the indenter, but this resulted in penetration every time, and the sphere did not deform as shown in the figure. Why is this happening? How can I solve this problem?