Open Ship Editor and create new ship based on template ship (in my case was Tombolo II) see that the Save buttons are available. Begin working on the ship building, modifying etc and Save buttons become light grey and can't save anymore.
#Save As and Save buttons become greyed out while working on new ships in Ship Editor [0.14.4.7]
copper burrow
dry brook
Win10Pro US, no mods, 4.9
I was unable to reproduce; I was able to save within the Editor but, when I tried to exit to the main menu with auto-save turned on, I got an NRE. At the same time, the game was in Pause mode (because menu) while the Saving dialog window was shown. Pressing the space bar did not unpause, but it did make the noise for that. Saving thing did not go away after a few minutes, so I Exited the game gracefully and that worked.
Weird either way
I did not get the lighter/greyed out buttons at all, though they are clearly visible in OP's post.