No worries, I know exactly what you mean.
One of the hardest concepts to come to terms with in Lumion is how reflections work.
What you're seeing is not a bug, but rather a limitation which is present in many real-time 3D engines.
Since the hardware is not fast enough to calculate raytraced reflections in real-time, there are just 2 options:1) Planar reflections:
This is perfect for mirrors. The downside is that the render engine basically has to render everything that is reflected a second time (mirrored), and depending on the scene complexity this can drastically reduce performance. This is the reason you typically only see planar reflections in small scenes in real-time 3D graphics. This feature is not (yet) available in Lumion.2) Cubemap reflections:
Also known as "faking it"
What you are seeing in the "mirror" above is a 360 degree panoramic reflection texture which is rendered from a single point in the scene (this point is set by adding the Lights/Utilities/Reflection Control
object to your scene).
This 360 degree panoramic reflection texture is then projected onto all reflective materials in your scene, including the "mirror" in this example.
The downside is that it is a rough approximation, and you will never be able to achieve perfect reflections with this method, but it's all we've got in Lumion for the time being.