rViz can't move Start State or Goal State in the Y axis via the UI

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I have a custom URDF; I haven't done all the work on it; so I must check if I can share it publically; appreciate that might hinder support; but perhaps I can still get some additional debug pointers.

I have used the moveit_setup_assistant and am launching the generated demo.launch file

In the UI I am unable to move the Start State or Goal State blue spheres in the Y axis; I can only move them up or down in the Z axis (the body does not have any freedom in the X axis by design)

If I go to the MotionPlanning - Joints tab; I can control the rotation joint which moves the Goal State in the Y axis; and then, if I go to Planning and click Plan; I do see an animation of the arm moving to the desired Goal State; which now includes a change in the Z axis.