I am having the same issue, when you get to 240, the schematic is still red, and when you go to learn it anyway, it will tell you that you do not have the proper crew skill to learn this. I am thinking it is a bug, tho it kinda crushed me when I got there and it said that. Was hoping the only item mod I would have to hunt down all the time would be armor mods. Was hoping to be able to make purple for all other things.