Spawning meshes to a Splines - meshes wont spawn on the spline - why do I keep getting an error about the default scene root not being static?

[TheWraeth]

I am using splines to preview the path the player character will take . I spawn a actor (Nav Preview) that holds the spline when left mouse is held . That actor holds the spline. I then call a function on the Nav preview actor to add meshes to the spline using Add Spline Mesh Component node . It compiles well but no meshes are visible in runtime. When I exit run time i get the following error (broken in two parts - its too long to screen shot at once)

It says that the default root of the Nav Preview Actor is not static so it cant attach the mesh. I know its something small but I have no idea what I am missing?
Thanks

[RecourseDesign]

Hah - yes just had that error for the second time last night - change your Blueprint Actor and Spline to “Static” mobility (unless you’re moving them in game).