Reflection stops reflecting at certain viewing angles

[ike709]

Another video!

Watch the floor as I move the camera. Notice any issues with the ceiling reflection?

[miyoyo]

This is because the reflections are made using the "Screen space reflections" method
The rendered parts of the screen are used by a shader to enable reflections on surfaces, this method has the advantage of being quite simple, completely dynamic (the reflections are actually the objects you can see), but it can only reflect what you can see, and if lights are out of your vision, they won't be reflected

https://www.youtube.com/watch?v=Y0as3vWTWzQ for a more "visual" explaination