Foliage Mode: Paint, Collision not working

[BugSwat]

I am using “Foliage Mode” / Paint and put down multiple stones and trees at once.

I am have set “Collision Presets” to “BlockAll” for both.

Both are “Static Mesh”.

The rock is the default “SM_Rock”.
The tree is from a package I just randomly got for free from the FAB.

The trees collide with my default BP_ThirdPersonCharacter.
The stones do not.

If I just put a stone down with drag/drop, as an StaticMeshActor, it will not collide.
What am I doing wrong?

Is the stone not able to collide, somehow?

[BugSwat]

This seems to be the answer: Cannot set collision for SM_ROCK - #3 by SE_JonF

But I don’t understand it.

Could someone please explain? In simple words? And small sentences?

[BugSwat]

Ok, got it.

Edit SM_Rock.

Collision / Auto Convex Collision / Apply

That is it. Whatever “it” is.