Landscape splines are displaying their collision incorrectly. The collision is projected off the spline however this issue is purely visual. The collision itself still works as expected.
This was tested and reported in 4.25.3 (CL-13942748). This was reproduced in 4.24.3 (CL-11590370) and Main 4.26 (CL-14154180)
Results: The collisions boxes displayed are always facing the same direction, and are following the curve of the spline.
Expected: The display of the collision boxes should follow the meshes' shape of the landscape spline.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-97702 in the post.