cartesian_velocity is 0

[Nimolty]

Hello, thanks for the fantastic repository! I try to use the velocity control (run_dynamic_cartesian_velocities.py). However, I found that the robot state's cartesian_velocities are all 0. So the run_dynamic_cartesian_velocities.py won't work. I am using a custom gripper (Robotiq_2f_85). Could you please give some advice to solve this issue? Thks!