Gazebo simulation unexpected behavior for joint 4 #375

When i spawned the robot into gazebo and using my custom controller to maintain the joint position of 4 at -1.57/1.57 but the robots seems to have a issue maintaining that position . I always drops to its limit 2.07 rad. Even when i publish it using the ros2 pub method. I face the same issue.

But If I increase the joint damping to 10.0 it is able to maintain but obviously its wrong to do.