Collision on rock is vastly off?

See the pictures. This is the LargePlainsBoulder from the Epic KiteDemo project. I am trying trying to use it to create some larger boulders that can be walked on and around, however as you can see in the pictures, the rock is vastly more detailed than the collision. The collision is a custom collision already on the mesh, and creating new ones through the engine does not help.

Any help would be appreciated.

the best way i would suggest is to create your own custom collision within a 3d modelling software (e.g. max, maya or blender etc). using primitive shapes to get the results best suited for what you need. UE4 auto collision seems to only work well on simple meshes, however i believe you can make custom collision within unreal using primitive shape, I’ve not done this personally though.