In thestarport screen, above the list of blueprints to build from, are what is intended to be filters (all, cost, core, user). 

They change order, but don't reduce the content in the list. 

In adition, I can't click "build nothing" after having built something. 

Admittedly, I never got the hang of that in GalCiv 1/2, and ended up permanently trying to delete the (default designs) - so maybe I'm just misunderstanding it.

Behavior I'd expect: "user" lists only my designs, "core" lists yours, "all lists all.