unity – How to produce interreflections in Unity3d?

Notice how the “door” here appears multiple times in the reflections, both vertically and horizontally. These “extra” reflections are called interreflections. I am trying to reproduce this effect in Unity3d.

There are docs for interreflections, but following the provided steps does not produce any additional reflections. I spoke to a few others who also had a similar problem–it seems that increasing the bounce count alone does not produce interreflections.

So how can I do it? What are the additional steps required to do this? Is this effect not called an interreflection? If so, what is it, and how can I produce it?