DoF Focal Distance and Region not respected in Mobile/Metal Preview or Deployment

When using a DoF setting and in Mobile Preview/Metal or launching on a iOS device which supports Metal, the DoF Focal Distance and Regions are ignored and the whole scene has DoF applied to it.

1. Open a Blank Project with No Starter Content
2. Add a Few Cubes in Level for Distance reference as needed
3. Add an unbound Post Process Volume
4. Set the Depth of Field settings to the following:
   -Method=BokehDOF
   -Focal Distance = 500
   -Focal Region = 500
   -Scale = 2.0
5. In Editor Preferences, turn on Metal Preview in Experimental
6. Under Settings, Preview Rendering Level, choose High End Mobile/Metal

RESULTS: DoF no longer respects Focal Distance and Range

EXPECTED: DoF still respects Focal Distance and Range (behavior in 4.9.2)