I have been trying to solve this same issue, except my paths are floating below the surface, not above. My aprons are also floating below. I have tried adjusting the ALT in the gizmo for various taxi points. They just snap back to where they were. I have tried flatten airport. I have tried a flatten poly. All existing airport categories are deleted. I’ve tried adjusting the runway terraforming falloff distance. Nothing seems to work. There is no green “Debug Shape” around them either which so many posts have mentioned causes terraforming issues (Since no one was kind enough to explain where they found these it’s DevMode Menus>Options>Terrain>Debug Shapes) . This SDK is beyond frustrating. Tons of bugs and no documentation.