Hull upgrade only available on the planet producing the metal

[Maethor]

A brief description: If you produce vulc or mag on another planet in the system, you cannot upgrade hull using those materials on another planet unless you produce the material from a smelter.

I had a world that had vulc, but didn't produce it there and the option to upgrade hull wasn't there until I placed a smelter and had it make vulc.

[Deantwo]

I assume this is because the airport repair shop only looks for materials in its locally connected buildings. So it isn't able to see the Vulcium that the other worlds have.

You can probably workaround this issue this by building warehouses in the other world's city to store the Vulcium (and other metals).