No shadow cast after Static Mesh Editor material assignment

This is a Rhino file. Shadows are not cast on the Static Mesh after materials are assigned in the Static Mesh Editor.

This was reported and tested in 4.24.3 (CL-11590370). This was reproduced in 4.25 Preview 7 (CL-12759524) and Main 4.26 (CL-12945139)

1. Open the UE4 Editor and create a Datasmith enabled project
2. Import the attached file via Datasmith
3. In the Level change the Lighting to Movable
4. Open ON_brep_7 in the Static Mesh Editor
5. You may need to zoom out, hightlight, and focus with the F key if using 4.24
6. In the Static Mesh Editor click on the Mesh Editing tab and click Edit Mode
7. Select the arrow beside Single and select Smoothing Group.
8. Click the center column and then Assign Material. Save the Mesh
9. Put something underneath ON_Brep_6-10 so that a shadow is cast
10. Observe On_Brep_7

Results: Object does not cast shadow for materials that were assigned w/in the SM editor

Expected: Shadow appears as before SM editor material assignment. Material assignment does not affect shadow