UCX Collision Not Working

Hi, I’m trying to get UCX Collision to work on a mesh and I’d like the top of it to be more or less identical to the mesh. The problem is that when I duplicate the mesh in Maya and set it to UCX, it doesn’t import to Unreal (using UE 4.13 preview 3) properly–it doesn’t show any collision. However, if I create a custom simple collision in Maya, it imports and collides just fine.

Just to clarify, this does not work:

And this does work:

I’ve tried triangulating the simple mesh as well and it still works perfectly fine (to rule out quads vs tris as the issue). Is there some kind of best practice that I’m missing?

The most important thing to look for when you want to use UCX collision, is whether the collision shape is convex. From your screenshots, it appears that neither of the shapes from your screenshots are convex.
Also, the simpler shape is better, as the probability that you actually need collision as detailed as in your first screenshot is very low (but depends on your game).

To work around the convex hull problem, you should separate your collision model into several shapes, and name each of them UCX_modelname_01, 02, etc.
If you absolutely want the visual model to also be the collision model, you can set “Use complex as simple” in the static mesh editor. In that case, you don’t need a separate collision model.