I'm trying to figure out what the problem is with the vanishing core ships. I got this bug the other day, and reinstalling didn't fix it. I have a small theory, but want to confirm whats happening to other people. Please post what Core ships do not show up even after researching the needed technologies. Also, please specify if you are also missing some hulls from the ship builder. I haven't seen a reply from stardock on any of the posts about this issue, so I don't know if they are working on it, already fixed it, or have it on a "todo" list. Narrowing down the problem will help get a fix faster.
Thanks