Scale by Safe zone setting for Scale box does not scale children as expected

Children of a scale box that is set to Scale by safe zone do not appear to scale as expected.

1. Open editor
2. Create a new widget blueprint
3. Delete the canvas panel
4. Add a safe zone to the designer tab
5. Add a scale box as the child of the safe zone that was added
6. Add an image as the child of the scale box
7. Set the size of the image to 1920x1080
8. Set the scale box to Scale by safe zone
9. Use the command "r.DebugSafeZone.TitleRatio 0.9"

Result: The Scale box appears to be the correct size, however the image appears to extend into the areas outside of the safe zone
Expected: The image would be scaled so that it is completely inside the safe zone.