I was actually just about to give up completely on the seed and try something else altogether, and deleted most of my prompt that was trying to specify colours, shapes, etc. Now that I think of it, I usually have better luck with a simpler prompt.

(professional photography:1), (epic lighting:1), (geographical landscape shot:1), (exotic alien planet) (high resolution, 4k hdr)

Negative prompt: blurry, out of focus, bad drawing, sketch, text, annotation, writing, font, letters, ((people)), ((watermark))

Steps: 30, Sampler: DPM++ 2M Karras, CFG scale: 8.5, Seed: 1575107236, Size: 768x512, Model hash: bfea7e18e2, Model: AbsoluteReality, Version: v1.4.0