unknown error on level blueprint

Hi guys,

i´m using a a custom event to drive the player Character through a spline inside a blueprint on my level for which a use a target null (as shown in the image)
What happens is that everytime i edit that blueprint, i have to manually refresh the target point on the level blueprint cause it gets broken.
Any ideas of what may cause this?
Thanks in advance.ea68bb6c2e71acf18dfcaf42f92b1902161e8e98.jpeg