Are you able to teleport? If not then the line trace is not colliding with CesiumWorldTerrain and you would have to review the collision object type that the CesiumWorldTerrain is.
Does this happen when you are in normal view? Or only when you are in earth view (as your picture shows)
Are there any custom shaders applied to the CesiumWorldTerrain? If it is translucent and has a higher sort priority than the line trace renderer’s material, the world would show up on top of the line trace.