Image stops evolving after 15000 polys

[Xaue]

After hitting 15000 polys the image will continue increasing in generation but will be no longer generate any polys.

[Tux3]

If you look in the settings, there's a minimum of 15000 and a maximum of 150000 polygons, it's supposed to be used if you want to get the best possible picture out of a fixed number of polys.
When the minimum is reached, it stops spamming new polys and tries to improve the existing ones, but the current algorithm isn't very effective.

So to keep getting the usual behavior, just raise the poly minimum in the settings.