Any more details? Is it a bonus not working? No money? The default map options were changed recently have a 0 multiplier for units (biters), and a 1x multiplied for worms and nests (mod settings -> map settings). This behavior is the same as the vanilla wave-defense scenario.
I don't see anything in IR2 to explain why it would have any conflict for credits, though maybe some bonuses are missing (ammo/damage types...)
