Box Reflection Capture artifacts

I’m trying the Box Reflection Capture and find a problem. See the pic, the reflection in the red box should be cut off its right part due to the wall, yet it has not. Is this normal? How to avoid it? I’m using only one BRC, but in a large map with many BRCs, checking this artifact manually is not practical.

This is because of the position of the reflection cube. The reflection cube creates a “reflection Map” at the position of the center of the box. The Engine only moves the reflection map on the ground when you move your player.
If you want to cut off the part with the wall you can either use Screen Space reflections or try to relocate your BRC.
But the best solution is this powerful tool of UE:

Planar Reflections

Thanks for the detail info. I don’t understand the mathematical behind, so if that is required to avoid the artifact, I would just avoid using the BRC for now.

BTW: I cannot get the artifact off by relocating the BRC. Yet the tutorial seems OK with the effect (as the pic shows), I’m really curious how it achieves that.