I'm not sure what you mean by Mod 0 or Mod 13, but I'm seeing what might be the same or a similar problem. Also on 0.72 opt-in, I designed a ship and saved it, built several, used it as a model for an upgrade, built several of them, but then when I went back to design another upgrade I could not find my ship on the list. I had to design a new one from scratch. The last ship in the list doesn't look like it's showing completely, but it's not just half of it like you describe.
Oh wait, by Mod 0 and Mod 13 you mean that the first design was Mod 0 and there had been 13 upgrades?
Edit: Unfortunately, when I load up the saved game the design that had disappeared is there again. So much for sending in a game that shows the problem.