Using franka, the object on the gripper fall down after using moveit to grab the target

Using the moveit ros example in the sample, use rivz to control the movement of the robotic arm and send instructions to Isaacsim. When I close the gripper and move franka, the object will fall.I tried creating a small cube and setting friction and other properties to the object, but still couldn’t solve the falling problem. How should I modify the properties so that the object does not fall? Thank you.
2024-04-19 18-02-51 00_00_00-00_00_30