I am not really sure if this is caused by this Mod but I suspect it because it only affects production costs in the armory which are only manipulated by this Mod (and not by any other mod that I have currently active).

When I select the highest difficulty I can see the increase in facilities construction times, the increase of soldier recruitment cost, the enemies health and armor increase and everything else but the only exception are the armory production costs which remain the same as originally intended for the first tree difficulty levels. The highest difficulty cost increases are not showing neither on the items affected by this mod (Predator Armor costs with cost multipliers) nor on the production costs not affected by this mod (Mimic Beacon, etc.)

Similarly I suspect also that this mod is blocking the effects of other mods that modify the cost of basic Armory Items such as Consume the Mimic Beacon mod. If this is the case and it is unavoidable , which is understandable considering the nature of this mod, It really wouldn't matter that it affects other "armory costs mods" as long as this mod is updated so that it allows us to change the cost also of basic items ( smoke grenade, etc.) in its own .ini file.

I hope this helps ;)