Hey ,
I just ran a simple test on my end and did not get the same results. Our set up is a bit different, and is probably part of the reason you are not getting the results you are expecting.
Firstly, you seem to be missing a skylight, which is important for outdoor scenes and establishing a reflective environment. Be sure to keep it set to stationary and disable shadow casting. Secondly, I set my lighting quality to the ‘Production’ level as this has an affect on the overall rendering quality of your scene after running lightmass.
Thirdly, I disabled the ‘Auto-Exposure’ setting within the Post process volume by setting the Min and Max brightness to 1.0 for each value field. I also did not touch the quality levels of the SSR section and left its values at default. I also deleted my exponential height fog, but this is optional. Below you can see the results I produced with my scene set up, which are very clean and working as expected.
Reflection Scene Set Up
The fuzzy artifacts you are seeing in your capture cube are due to ‘Temporal AA’ attempting to reduce aliasing on the edges of of your objects in the scene. To correct this, and to save performance, uncheck the ‘Capture Every Frame’ checkbox in the details panel of your Scene Capture Cube actor.
Scene Capture Cube Texture Target
Here you can see I have produced a pretty clean result with the set up I am using. In my case, I create a material instance so I could play around with the Base Color, Metallic, and Roughness values to get the right reflections. Set our roughness to something like 0.1 to get a glossier feel.
Let me know if you have further questions or need additional assistance.
Cheers,