Niagara Particles are not colliding with scene objects

Hi. Im making a cinematic and i am having some problems with the Niagara Particle System. I have a vehicle loaded with a mini gun running a mock doing donuts and all sorts. Anyway i have managed to get this particle system up n running where the particle generates a hit particle response which generates sparks only the particles are colliding with the floor ok but not the other objects in the scene. Now i managed eventually to get the particles to collide with the surrounding rocks, only I have no idea what i did to get that to work. in my scene I have some basic geometry for Collison testing. How do i get these particles to react to the geometry in my scene including reacting to Alembic Objects? I am not using a blue print. It is a strait forward Niagara particles system. Iv watched a ton of videos and so far nobody has mentioned what to do if the collisions don’t work because the collisions seem to work for everyone except for me. Yet as you can see in the video, i am getting collisions, just not on the objects and only some rocks are reacting to the collisions. This sucks.