I have seen this happen at a shipyard of mine that belonged to a Core world of mine that got conquered by an AI Race coming out of a nearby Subspace line. Once I took back the Core World, I think that the Ship Yard returned to normal. This happened in a recent 0.40 game, but I am sure 0.45 will behave the same.

I think if a Shipyard has NO input production (because the source got captured), it runs into some divide by zero problems to calculate how long it will take to produce ships, and the GC IV program sets the times to 1 rather than some really large number that is the computer's equivalent to infinity, i.e. the largest number that the computer can generate. Which depends on how numbers are handled on your computer. All computers have a range between the smallest and largest numbers that they store and process, it depends on how they handle integers and floating point numbers on that computer, and is operating system and computer dependent. It also depends on how many bits are being used to store those numbers. There can be several different types of integers and floating point numbers being used on the same computer for the same program, i.e short and long and even very long forms, as well as signed and unsigned. See books on computer programing and computer languages.

These ships will never be produced until the Ship Yard regains a source of input production by you recapturing the Core World that sponsored it, and the construction times get reset to realistic figures.