Normal maps for walls, floors, columns and friezes do not function indoors

I’ve noticed that the normal maps for wallpapers, floor tiles, columns and friezes do not work in interior lighting conditions. This effect that is used to achieve a more 3D look on a 2D surface only works outdoors, or when there is direct sunlight casting through windows and doors.

For demonstrative purposes I made versions of these specific assets with a blank grey diffuse texture, so that the effects provided by the normal maps are more easily visible.

Here’s the wallpaper, floor tile and column in outdoor lighting:

And here in indoor lighting:

Here’s a comparison with a frieze:

And for some added emphasis I also made blank grey swatches of a tile rug, a fence and a spandrel to show that normal maps do actually work indoors in other types of assets:

Here’s another image that shows how the normals of a wall and floor are visible only in direct sunlight coming through a window:

This is all rather unfortunate, because the normal maps add a nice touch of extra depth. Especially for flat surfaces such as walls and floors. Many wallpapers for example are designed to be primarily used indoors, and so it’s a shame their normal maps don’t actually work properly.

Tested without CC, mods or customized visuals. (Only exception being the images used for conveying the provided information.)