Surface environment-obstacles problem

Hi ;
I want to put an obstacle in the surface environment in Physarealm plugin but it doesn’t see the obstacles I put. What should I do to see it? What type of obstacles should it be?

Also, after creating the route I want, the herd starts to disintegrate. What should I do to avoid separation?

Can you help me?
21.02.2020.3dm (47.5 KB) (24.1 KB)