Scene Depth appears to return zero on iOS

Scene Depth appears to return zero on iOS. In this test the material applied to an image does not appear to lerp between 0 and 1 for the various objects in the scene, implying that the Scene depth node being used returns only 0. Zero is the suspected result due to the result being the same as if Scene depth were replaced with a constant of 0.

1. Download attached project
2. Open attached project
3. Play in eidtor
4. make note of the UMG image and of how the scene looks on it
5. Stop PIE
6. Launch on to iOS device
7. Notice that the UMG image widget is solid white

Expected: The image would look the same as it did in PIE
Result: The material applied to the image does not appear to lerp between 0 and 1 for the various objects in the scene, implying that the Scene depth node being used returns only 0.