Problem importing Maya Custom Collision (it's showing with less vertices inside UE4)

Hello, im importing a custom collision into UE4 from maya, i have checked that it is well named(Render mesh is: BaseLowPoly, and Collision is: UCX_BaseLowPoly_00), I also tried other names for the collision mesh like: UCX_BaseLowPoly_01, UCX_BaseLowPoly_001, and UCX_BaseLowPoly, I tried to use obj instead of fbx, but each time the collision is imported the same, and I lose important detail because otherwise is like the character is walking on air on top of the surface.
I hope you can help me, thanks in advance