I want the emissive mesh to reflect only in the mirror.

I want the emissive mesh to be invisible within the actual space, but only reflected in the mirror
I tried this video and it worked in Default viewport, but in Cinematic viewport and ingame, the emissive mesh is not visible in the mirror.

Does anyone know what causes the mirror to stop working on Cinematic viewport or ingame?

My UE version is 5.1.1 and now using Lumen