The cap of a sliced procedural mesh is not affected by lighting

After slicing a procedural mesh, the cap on the sliced end does not seem to be affected by lighting. This can result in the end looking dark.

Test content submitted in Dev-Framework at CL 3050416

1. Open QAGame in editor.
2. Open the level TM-SliceProcMesh.
3. Play in viewport.
4. Press R.

RESULT:

The meshes are sliced, and the ones that have caps are not affected by lighting.