Reflections Rendering Incorrectly in SM4

Reflections are rendering incorrectly in Rendering Preview Level SM4 in 4.18, but were working as expected in 4.17. This is a regression.

When I reproduce the issue, I get results similar to issue from JIRA [Link Removed]. See attached Screenshots.

1. Open attached Project in 4.17
2. Change to SM4 (Settings > Preview Rendering Level > Shader Model 4)
3. Notice the quality of reflections looks nearly identical to SM5
4. Open same project in 4.18
5. Change to SM4 (Settings > Preview Rendering Level > Shader Model 4)
6. Notice the quality of reflections compared to SM5 is very poor.
   Result: Reflections appear only on outer edges of spheres. There are large grey areas with no reflections. Screen shots attached.
   Expected: Reflections in SM4 look same in 4.18 as in 4.17.

Reflections misbehaving in SM4 in UE4.18/4.18.1