When I have Space Exploration and UndergroundPlus activated the rearch costs for the Fast Conveyor Tunnel 1 is super high.
You need red, green, yellow and rocket science and then you need space science, production science, Material 4 science and Deep-Space 4 Science.
So this is clearly a bug. I know the last time this mod was updated is two years ago but maybe there is a chance the mod creater looks into it.
