The spline path editor is still a bit buggy for me. Sometimes it works, other times not. Today, the nodes are appearing at the centre of the screen again. I've noticed that when this happens, the blue box representing the main node is missing.
Also, sometimes you can select and move the individual nodes around, other times you can't. Not only does the node remain frozen, but you can't select any other nodes. The system can go from working to non-working within the same scene, so I'm not sure what the pattern is.