Alien Biomes: Prevents creep?

There have been reports that Alien Biomes is preventing vanilla enemy creep from spawning. Some people have said it stops tiles from being placed, but I don't think vanilla has creep tiles so my guess is it is just a lot of decals. I'm not sure why the decals wouldn't be placed unless they are colliding with decals that Alien Biomes already has placed.

Anyway the task is figure out what is happening and why. It is mostly just going to be loading the game with different settings and seeing what spawns so it is time consuming but not difficult. I'll probably do the final fix myself once we know what the problems is, just because it's hard to undo changes to terrain generation.