Custom Ship Issue

In my shipyard, it shows that I can construct a "Swordfish M4" which is a Cruiser class (first screen snapshot below).  I wanted to create a modified version of this ship and then construct it.  I went into the Ship Designer and said that I wanted to modify the "Swordfish M4".  When I was done modifying the ship I saved it under the name "Custom Cruiser 17" (second screen snapshot below). However, when I exited the Ship Designer and went back into the Shipyard screen, my new ship design wasn't there (third screen snapshot below).

When I look in the Designs folder I can see the 2 files for the "Custom Cruiser 17" ship (fourth screen snapshot below).

What is going on?  Is there a setting somewhere that hides custom designs?

I have created a link to a save file in case that will help you determine the issue:

https://www.dropbox.com/s/8i6p7zszog14kxh/Ship%20Issue%20Under%201.50.373846.GC4Sav?dl=0