Landscape Spline issue - meshes not combining into single road

I’m trying to make a road on the terrain I’ve made so I’m testing the landscape spline tool. I’m sure I’m making a rookie mistake, but I can’t for the life of me seem to get my road meshes I’ve made to join up. There isn’t a huge amount of info on landscape splines online and the UE documentation on it assumes they will join so I’m wondering what it is I’m doing wrong.

Has anyone ever had this issue?