Yes, its checking if the mesh has any overlapping actors of different collision channels.
In your case its overlapping with the ground.
You can either change the collision rules / remove them completely or again change the pivot point so that he is really below the mesh.
It is annoying to do that stuff but once you got how it is suppose to be it is fairly easy.
You trace and you set the pivot point of your mesh to the impact point, so the pivot point is going to be at the top border.
But you need a small gap between to make sure its not overlapping.
Later on you would change the mesh a little bit and the collision checks to make sure it works on actual terrain.
Yes im going to do that.
No thanks i got that already with disease and deacying food and such stuff… sooo much fun to make ! 