It's not bugged, just activated differently than other modules. I figured out I need to hit the Y key to bring up the backpack and cursor, then use the cursor to select either the arrow key or the activate key to make the item. All the modules should work the same way throughout the game as some modules use <hold X> to use or <hold Y> to examine and <A> to activate, while the Printer and Vehicle Bay use Y to bring up the backpack and cursor. Be consistent in how the game works to avoid confusion. Good job overall with the game though.
One thing I didn't like is how easy the medium rover is to overturn when driving, and then it can't be righted again. Finally ended up bulding a large rover and using it to turn. the medium rovers over. Now I have train with medium rovers.