Letter Boxing Appears In Planar Reflection Capture When "Constrain Aspect Ratio" Is Checked

When constrain aspect ratio is checked on a camera it will add black bars if the destination view has a different aspect ratio from the camera. These black bars will appear in the planar reflections.

Note: Extra FOV seems to influence how large the black bars need to be before the start appearing in the reflection.

1. Open attached project (PlanarRefBB.zip)
2. PIE
3. Adjust the size of the viewport in the editor to that it causes letter boxing (like in screenshot)

RESULT
Black bars appear in the planar reflection.

EXPECTED
Letter boxing occurs, but it isn't visible in the planar reflection.