SSR not rendering correctly in SM4 Preview

This is a regression from 4.17.2 and you do not need to be in PIE to see the effect.

This is not seen in Shader Model 5

1. Open QAGame
2. Open TM-ShaderModels map
3. Select Settings->Preview Rendering-> Shader Model 4
4. Wait for shaders to compile
5. Navigate to Example 15

Result: Top half of the SSR is not rendering correctly