It doesn't seem to be working, I've added it mid-playthrough though, can this be the issue?

Playing on Nauvis, expansion installed, other mods present but none that should affect the same thing.

The mod only triggers when a resource depletes. The effect is rather subtle. I have it in on my playthrough and it definitely has left an impact on the starting resource patches. It's way more noticeable when you decommission a mine.

As for other planets... Vulcanus and Fulgora don't have a whole lot of variety in the tiles so it's harder to notice.