I’ve tried to look at your figures again.
The joint is tracking the Target position correctly. (So I should have been able to deduce that you set the payload and Center-of-Gravity correctly)
Robot movement is dependent on what type of move you are doing.
If you are doing a moveJ, then the robot will try to move the Tool to the target position as fast as possible.
The pathPlanner might do some weird shaping, since the robot is not infinitely rigid.
The pathPlanner is primarily concerned with the position of the tool, not so much the angle of individual joints
Have you considered to look at the tool position instead of a joint?