My robot's Jacobian becomes zero when the robot gripped a cube in Isaacgym, not moving after get in contact with the cube

I followed the official example with a custom kinova Jaco 7DOF arm. The robot arm is moving well when not grasping the cube, however the robot freeze after gripped the cube. I printed out the Jacobian matrix at the freeze moment and found that the 6X7 jacobian matrix elements all becomes close to zeros. Why is the case happening? Is that because of the simulator issue or anything else?
Here is the frozen robot after gripped the cube:

Here is the plot of the Jacobian matrix elements values, which all decays to zeros after the robot gripped the cube: