What is going on here? It’s just a simple emissive material, and only shows up in the packaged game.
Did you mark it as a light source?
Have you checked the room in the Lumen Scene view?
small emissive meshes are not well represented in the lumen scene and can miss the probe evaluation/update phase on the lower light grid sizes. you should put an analytical light in the same spot. or if you use megalights 6 area lights would be the “proper” way to reproduce the shape and cast of the lighting and shadows.