The instructions for any Ground2K created scenery insist that the filenames in SCENEDB/WORLD/TEXTURE & TEXTURE must match.
I think it's because the sim looks in both locations for the texture bitmaps to be present.
Interestingly they don't have to be the same image, but the bitmap names must be there.
If an image is present in one location but not the other, the sim struggles to know what to display & so defaults to the long-range blue/brown/green low Level of Detail (LOD) rendering.