Maybe bug with manufacturing.

[Nord]

No bug reporting theme on a whole forum, so put it here. Too lazy to register  on github, sorry.
If one want to produce a craft, using another craft as material (in a mod, of course), like craft upgrade or something, will need two hangars to start manufacture. Then one hangar will go empty again.

[The Reaver of Darkness]

Oversight, might not be fixable. You can turn the craft into an item and then into a craft to circumvent it, though it's an annoying addition of manufacturing recipes.