Don’t see why to be honest, I wouldn’t have thought the perception system would care about anything like that really. Maybe the calculated actor bounds are having some effect, since they would change as you changed the mesh, but I don’t know why they would affect perception.
Only other thing I can think to check is the pivot point of your player mesh. If the pivot is at the bottom of the mesh, it could be being blocked by the ground. You could try replacing the mesh with a basic sphere and see if that makes any difference.